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Book._bLa_ 

GopyiightN n _L®i-j_ 

COPYRIGHT DEPOSED 














ELECTRIC-WIRING, DIAGRAMS 
AND SWITCHBOARDS 







Electric Wiring Diag rams 
and Switchboards 

A PRACTICAL, COMPREHENSIVE TREATISE 
EXPLAINING THE THEORY AND DESIGN 
OF WIRING CIRCUITS 

A GUIDE FOR ALL INTERESTED IN THE APPLICATION OF 
ELECTRICITY TO ILLUMINATION AND POWER 

The Design of Switchboards for Lighting and Power is Treated; 
Wiring of Single-, Two- and Three-Phase Circuits with various 
degrees of Inductance is given. Converting Apparatus in 
connection with Single-, Two- and Three-Phase Cur¬ 
rents, also Transformers and Measuring Instru¬ 
ments and Alternating Current Induction 
Motor Wiring suggestions are included. 

BY 

NEWTON HARRISON. E.E. 

<1 

WITH ADDITIONS BY THOMAS POPPE 
Author of “House Wiring,” etc. Associate Member Institute Electrical Engineers 



THIRD EDITION, REVISED AND ENLARGED 

ILLUSTRATED BY 138 ILLUSTRATIONS AND DIAGRAMS 


NEW YORK 

THE NORMAN W. HENLEY PUBLISHING COMPANY 

2 WEST 45th STREET 

1 920 



















Copyright, 1920, 1916 and 1906, by 
The Norman W. Henley Publishing Company 


Printed in the U. S. A. 





9 \m 



PRESS OF 

BRAUNWORTH & CO. 
BOOK MANUFACTURERS 
BROOKLYN, N. Y. 


©CU566749 
9 vo- f. 


t 










PREFACE 


The contents of this book cover the fundamental 
facts of wiring, as well as such of the practise as its 
modest proportions could be well expected to embrace. 
It is not offered to the reader as a scientific treatise— 
though its statements will be found able to bear the 
light of scientific investigation—but as a technical 
work, in which the author has made an effort to pre¬ 
sent the underlying principles of wiring in language 
suited to the comprehension of the general reader. 
Though framed in accordance with the technical re¬ 
quirements of the art of wiring, the subject matter has 
been presented with the idea and intention of making 
the reader independent of it as soon as possible. 
Though a mastery of the principles of rational wiring 
go hand in hand with its practise, it is frequently 
found easier to gain the practise than the theory. But 
it is also true that the best equipped in this particular 
field of work are those whose power lies within the 
head and hand, to an extent which makes them inde¬ 
pendent of text-books or other references. To gain 
this much-to-be-desired equipment, a knowledge of 
what is best and most useful must be obtained. What 
the author considers to be just such knowledge, is pre¬ 
sented here in a logical form, as far as its various 
successive steps are concerned. 

5 


6 


PREFACE 


The elementary relationship of volts, amperes, and 
ohms is given first consideration; then the pivotal 
point of drop of potential is emphasized and ex¬ 
panded, and the first applications of this idea brought, 
as is believed, clearly to the reader's attention. Means 
of calculating drop, finding the circular mils of the 
wire, and arriving at its numbered gauge size without 
a table are given. This may be regarded as the pri¬ 
mary object of the book, and will be considered by 
wiremen who master this method as well worth the 
slight labor involved. The further expansion of the 
simple circuit into others of a more complex type rep¬ 
resents the next stage of progress. From this step 
on, the subject matter leads into a consideration of 
the principles of switchboard design, with reference to 
shunt and compound wound generators. The appa¬ 
ratus employed on switchboards is of great importance 
in electric lighting. Though, as is commonly sup¬ 
posed, the switchboard represents the means by which 
all important circuits are concentrated and controlled; 
it is also the measuring and protective, as well as the 
distributing center of the electric light or power sys¬ 
tem. Wiring embraces this, as well as the moulding 
and pipe work, as will be readily understood by the 
intelligent reader. It is incompletely treated, however, 
unless the meaning of alternating current phenomena 
which relate to wiring; as well as simple arithmetical 
methods of getting the sizes of wire for such circuits, 
also receive careful attention. 

In this respect, the pages of this volume will prove 
of the utmost value to the student, wireman, or con- 


PREFACE 


7 


tractor. It is not to be inferred from this, that such 
knowledge is at a high premium; but it may be in¬ 
ferred that such knowledge is often inaccurate, 
incoherently arranged, and frequently useless. For 
such reasons as these the latter part of the book was 
written, and it is hoped that it will fulfil the purpose 
held in view. All that the author cares to claim is 
the manner of presentation; as it is well known that 
the greater responsibility for those formulas and their 
derivations, which are the veritable foundations of the 
science of electricity, must fall upon such masters as 
Ohm and Helmholtz. 

Newton Harrison. 


PREFACE TO THIRD EDITION 

The favorable reception of this treatise by the pub¬ 
lic has been gratifying, to say the least, and in pre¬ 
senting the third revised edition of this work, the 
Author wishes to thank his readers in the past and to 
state that the ever-increasing use of Transformers 
and Measuring Instruments has caused him to feel 
that data regarding these two subjects would be ap¬ 
preciated, therefore chapters have been included de¬ 
scribing the construction and application of these 
appliances. The increasing application of alternating 
current or induction motors, compensators and time 
limit relays has made the addition of a chapter cover¬ 
ing these subjects necessary in this edition. 

January, 1920 . 





CONTENTS 


CHAPTER I 

PAGE 

Introduction—Purpose of Wiring—Ohm’s Law—Drop of 
Potential—Meaning of a Milfoot—Meaning of a Cir¬ 
cular Mil—Calculation of Drop—Calculation of the 
Sizes of Wire for a Given Drop—Wiring Rules—Cal¬ 
culation of Resistance for Branch Circuits—What is 
Power and How Estimated.15 

CHAPTER II 

Carrying Capacity of Wires—Effects of Heat upon Resist¬ 
ance—Allowance for Heat—A Simple Electric Light 
Circuit—Wire of a 10 Lamp Circuit with Drop Analyzed 
—The Wiedemann System of Lighting and Its Defects 
—The Wiring Table—How to Prepare a Table of Sizes 
and Circular Mils—Examples of the Application of the 
Wiring Table and Formula—Calculation of the Drop 
per 1,000 Feet per Ampere.40 

CHAPTER III 

Elements of a Wiring System—Meaning of Mains, Feeders, 
Branches—Proportioning the Drop in the Various Parts 
of the System—The Center of Distribution—Examples 
of the Effects of Drop in Parts of the Circuit—Equaliz- 

9 


CONTENTS 

ing the Pressure—Dynamos for Incandescent Lighting 
—Effects of Changes in the Field of Dynamos upon the 
Lighting—A Wiring System with Four Centers of Dis¬ 
tribution—The Life of a Lamp. 


CHAPTER IV 

Measurement of Resistance—Principle of the Wheatstone 
Bridge—Balancing the Resistance of Four Lamps— 
Measuring a Lamp Hot and Cold—Measuring Insulation 
Resistance—The Insulation Resistance of Buildings 
Wired for Electric Lighting—The Three Wire System 
Compared with the Two Wire—Calculating the Three 
Wire System of Wiring—Circuits of a Three Wire Sys¬ 
tem with Two Centers of Distribution—Calculation of 
Pounds of Copper for Mains or Feeders . 


CHAPTER V 

Types of Motors—Connections of Motors—Meaning and 
Reason for Back Electromotive Force—Use of a Start¬ 
ing Box—Method of Connecting Up a Shunt Wound 
Motor—Horse Power of Motors and Efficiencies—Effi¬ 
ciency of Motors and Size of Wires—Advantage of High 
Pressures—The Alternating Current for Lighting— 
Meaning of Frequency or Cycles. 


CHAPTER VI 

Reasons for Employing Conduit—The Use of Cleats—The 
Use of Moulding—Iron Armored Conduit—Enameled 
Iron Conduit—Brass Armored Conduit—Asphaltic 


PAGE 


63 


87 


112 



CONTENTS 


ii 


PAGE 

Paper Tube or Plain Conduit—Flexible Woven Conduit 
—Flexible Metallic Conduit—The Use of Bends, El¬ 
bows, Outlet and Junction Boxes—Directions for In¬ 
stalling Conduit—Conduit Jobs and Their Accessories 
—Schedule for Wiring Systems.124 

CHAPTER VII 

» 

Requirements for Iron and Steel Armored Conduit—Laying 
Out a Conduit System—The Insulation of Conductors 
—Mechanical Work—Insulating Materials—Concealed 
and Exposed Work—Insulation Resistance—Grounded 
Wires—Soldering Solution—A Distribution Sheet for 
Laying Out Wiring.143 

CHAPTER VIII 

The Light of Incandescent Lamps—The Power Consumed 
by Lamps per Candle Power—Candle Power and Coal— 

Effect of Low Pressure on Light—Effects of Globes on 
Light—Size of Room and Number of Lights—Use of 
Side Lights and Chandeliers—Color of Room Decora¬ 
tion and the Lighting.158 


CHAPTER IX 

Switchboards and Their Purpose—The Parts of a Switch¬ 
board—Connections of a Shunt Wound Generator— 
The Circuit Breaker—The Rheostat—Connections of a 
Compound Wound Generator—Fuses—Connections of 
Two Shunt Wound Generators and Switchboard— 
Equal Pressures for Both Dynamos—The Bus Bars— 


12 


CONTENTS 


PAGE 

Back View of Switchboard Showing Wiring Connections 
for Two Shunt Machines—Connections of Compound 
Wound Machines Showing Bus Bars and Equalizer Bar 
in Service—Over Compounding—The Series Winding 
and Its Purpose.168 

CHAPTER X 

Generators for Alternating and Direct Current Lighting— 
Character of Lighting Done—The Switchboard for Two 
Compound Wound Generators—Connections to Instru¬ 
ments—Switchboard for Control of Six Floors and Two 
Elevators—Connecting Two Shunt Dynamos According 
to the Three Wire System at the Switchboard—Switch¬ 
boards for Electrolytic Work.188 

CHAPTER XI 

Panel Switchboards—Street Railway Switchboards—Con¬ 
nections of Compound Wound Generators in a Power 
House to Switchboard and Instruments—Lightning 
Arresters—The Panels and Their Functions—Station 
Fires through Lightning—The Generating, Feeding and 
Metering Sections.198 


CHAPTER XII 

Testing—The Ground Detector—Testing with a Volt¬ 
meter—Use of the Magneto for Testing Insulation— 
Locating Grounded Circuits—Damp Basements—Use 
of Insulators—Weatherproof Wire—Cables—Rotary 
Converters—The Applications of Rotary Converters— 
Efficiency of Converters. 



CONTENTS 


1 3 


CHAPTER XIII 

PAGE 

Important Features of Alternating Currents to Consider— 
Losses in a Line—Inductance Explained—Inductance 
with Alternating Currents—Resistance Compared with 
Inductance—Effect of Resistance and Inductance on 
an Alternating Current—Effect of Capacity on an 
Alternating Current ___ _ _ _ _ - 223 

CHAPTER XIV 

Calculation of Reactance—Value of Induction Reac¬ 
tion—Value of Capacity Reactance—Calculation of 
Impedance in a Circuit—The Unit of Self Induction— 

The Power Factor.233 


CHAPTER XV 

Circular Mils for Alternating Current Mains—Value of C 
for Single-phase Currents—Circular Mils Calculated 
for Single-phase Circuits—Circular Mils Calculated for 
Two-phase Circuits—Circular Mils Calculated for 
Three-phase Circuits—Average Power Factors— 
Weight of Copper—The Induction Motor—Syn¬ 
chronous Motors—Rotaries in Power Transmission— 
Rotaries in Electric Light Stations—Two- and Three- 
phase Alternator Connections - - - - - -242 

CHAPTER XVI 

Transformers—Containing Numerous Diagrams of Trans¬ 
former Connection—Single-phase, Single-phase Mul¬ 
tiple, Two-phase Four-wire, Two-phase Three-wire 
Secondary—Open Delta, Three-phase, Delta-delta, 





14 


CONTENTS 


PAGE 

Star-star, Delta-star, Star with Neutral—Testing 
Delta Connections for Accuracy—Boosting and 
Lowering Voltages by Using Delta-star Connec¬ 
tions—Voltage and Current Relationship with Volt¬ 
age Ratio of Transformation Explained - - - - 259 

CHAPTER XVII 

Electric Meters—Meter Connection Diagrams, Among 
Which are the Voltmeter (A. C. and D. C.), Am¬ 
meter (A. C. and D. C.), D. C. Wattmeter—Single¬ 
phase, Two-phase and Three-phase Wattmeter, Cur¬ 
rent Transformers, Potential Transformers—In¬ 
creasing the Capacity of A. C. and D. C. Voltmeter 
Using Resistance and Transformer ------ 274 

CHAPTER XVIII 

Alternating Current Motors—Multi-Speed Induction 
Motor—Adjustable Speed Induction Motor—Wiring 
Connections for Induction Motor—Connections for 
Three-phase Motors—Time Limit Relays—Internal 
Wiring of Compensator - -- -- -- -- - 286 





CHAPTER I 


INTRODUCTION.—PURPOSE OF WIRING.—OHM’S LAW.—DROP 
OF POTENTIAL.—MEANING OF A MILFOOT.—MEANING 
OF A CIRCULAR MIL.—CALCULATION OF DROP.—CALCU¬ 
LATION OF THE SIZES OF WIRE FOR A GIVEN DROP. 
—WIRING RULES.—CALCULATION OF RESISTANCE FOR 
BRANCH CIRCUITS.—WHAT IS POWER AND HOW ESTI¬ 
MATED. 

Introduction. —Wiring is now one of the most 
important departments of electrical engineering. In 
the last 15 years it has developed from a compara¬ 
tively haphazard attempt to conduct current to the 
various lamps in a building into a systematized 
code of principles and practices based upon the rul¬ 
ings of the Board of Fire Underwriters, in conjunc¬ 
tion with the recommendations of the most promi¬ 
nent society of electrical experts in the United 
States. 

It has in fact assumed an importance in the 
building arts second to none. No large structure is 
erected at present without provision being made in 
the plans for electric wiring. In many cases it has 
entirely superseded gas and is the only means of 
lighting considered. 

The development of the art of wiring has meant 
the development of industries dependent upon it for 

15 


16 ELECTRIC-WIRING, DIAGRAMS 

their existence. Immense amounts of capital are 
in use for the manufacture of insulated wire of 
many descriptions; for the manufacture of sockets, 
switches, cut-outs, lamps, lampcord, iron pipe con¬ 
duit, and a host of smaller appliances essential to 
the installation of a wiring system. The experi¬ 
mental stage has been passed and electric wiring 
and electric lighting have entered into the admin¬ 
istration of the affairs of our large cities as an 
economic measure required for public safety and 
convenience. So we enter, as it were, upon a new 
I era in the application of electricity for electric light 
and power, and this has had enormous influence 
upon the development and progress of every large 
city and town. 

Regarding the practice of wiring from such stand¬ 
points, it is easy to understand the importance to 
be attached to those principles which lie at the very 
root of the subject. When it is remembered, that 
the greater part of the wiring is still to be done in 
thousands of homes and buildings of the future; 
that the universal application of electricity for elec¬ 
tric lighting will become a fact as soon as the price 
of electricity is within the means of the humbler 
classes, and finally that its hygienic benefits are so 
pronounced both in summer and winter that it must 
in the course of time be regarded as an indispen¬ 
sable adjunct to home comfort; it will be seen that 
the art which will reach its greatest development 
and application in that direction for that purpose is 
electric wiring. 


AND SWITCHBOARDS 


17 


Statistics may be found in a variety of magazines 
showing the enormous growth of electric lighting 
in the United States, but one of the most unique 
records is that of the fan motor load which is ex¬ 
perienced at certain hours of the day in large cities 
during the summer months. 

Recently the New York Stock Exchange expended 
thousands of dollars in the construction of an equip¬ 
ment, largely electrical, for keeping the air of the 
exchange 10 degrees cooler than the air of the street 
during the heated period. Fans 12 feet in diameter 
are employed for this purpose attached to powerful 
motors. The air is filtered as it passes through into 
the exchange thus relieved of every particle of dust. 

Purpose of Wiring.—It is not only the distribu¬ 
tion of current which is kept in view by laying out 
a wiring system, but the proportioning of the sizes 
of wire employed so as to limit the loss of pressure 
from point to point as required. In the lighting of 
incandescent lamps it is necessary to supply a defi¬ 
nite pressure to the terminals in order to produce 
the requisite light. The incandescent lamp is pecul¬ 
iarly sensitive to changes of pressure, losing a large 
percentage of its illuminating power with a slight 
drop in pressure and gaining rapidly in candle 
power as the pressure increases. The life of the 
lamp is seriously affected by more than the neces¬ 
sary pressure; it rapidly blackens and soon becomes 
valueless unless such irregularities are checked in 
the power supply. 

Ohm's Law.—Few discoveries of modern times 
2 


1 


18 ELECTRIC-WIRING, DIAGRAMS 

rank in importance with the discovery of Ohm’s 
Law. A study of the principles of electric wiring 
cannot be carried on without the reader possessing 
a thoroughly intelligent conception of the meaning 
and application of this law. 

The law in itself is exceedingly simple, and ex¬ 
presses the relationship between amperes, volts and 
ohms. In order to understand the law the first 
thing to be done is to gain a knowledge of what is 
meant by a volt, an ohm and an ampere. In order 
to do this satisfactorily, illustrations must be em¬ 
ployed which though not presenting an ideal simile, 
yet will serve to convey the idea in view. 

Volts.—When a current of electricity passes 
through a circuit it is set into motion by what is 
termed electromotive force. If it is impossible to 
imagine water or steam or any other fluid passing 
through a pipe without pressure, it is likewise im¬ 
possible to imagine a current flowing through a cir¬ 
cuit without electromotive force. In other words, 
the force which moves or tends to move electricity 
is electromotive force. 

Electromotive force is measured in volts just 
as steam pressure comparatively is measured in 
pounds. The general expression, electromotive 
force and its measurement in volts, may be under¬ 
stood by reference to the general expression, press¬ 
ure and its measure in pounds. 

Amperes.—If a certain quantity of electricity can 
be delivered by a current in one second it is because 
the current has a certain strength. If the current 


AND SWITCHBOARDS 


19 


is capable of delivering twice as much in one case 
as another in one second, it obviously possesses 
twice the strength. A unit quantity of electricity 
is called a coulomb. The question now is, what 
is a coulomb? It can be answered in a practical 
manner by stating that every particle of copper,, 
silver, gold, nickel or any other metal in an electro¬ 
plating bath is carried over and deposited on the 
articles to be plated, thickly or thinly, according 
to the number of coulombs that have been em¬ 
ployed. For instance, one coulomb per second will 
carry over one-twenty-ninth of an ounce of copper 
in an hour. Each coulomb always carries over a 
definite quantity. Each second the same amount 
is carried over, so that in the course of oneHiour 
(or 3,600 seconds) a weight of copper equal to one- 
twenty-ninth of an ounce has been deposited. 

A current of electricity which will give one cou¬ 
lomb per second has a strength of one ampere. 
This means that a current of one ampere will plate 
over a weight of copper equal to one-twenty-ninth 
of an ounce per hour. If the current has a strength 
of two amperes it will plate twice as much per 
hour, and so on. A current of the strength of five 
amperes will give five coulombs per second, ten 
amperes ten coulombs per second, etc., as indi¬ 
cated in the table: 


20 


ELECTRIC-WIRING, DIAGRAMS 


Table Showing Relation Between Coulombs and Amperes. 


Strength of current. Amperes. 

Coulombs per second. 

1 

I 

2 

2 

3 

« 

3 

4 

4 

5 

5 

IO 

IO 

5 o 

5 o 

IOO 

IOO 


Table Showing Relationship Between Coulombs, Copper 
Deposited and Strength of Current. 


Amperes. 

Coulombs. 

Hours. 

Pounds. 

Ounces. 

Grains. 

I 

36,000 

10 



180 

5 

180,000 

10 


2 

26 

IO 

360,000 

10 


4 

52 

20 

720,000 

10 


8 

104 

3 ° 

1,080,000 

10 


12 

j 56 

40 

1,440,000 

10 

I 


208 

5 o 

1,800,000 

10 

I 

4 

260 


It is of great importance to grasp the meaning 
of Ohm’s Law, not only as an abstract relation¬ 
ship between current, electromotive force and re¬ 
sistance, but as a physical relationship, which may 
be proved by illustration in many ways. The fol¬ 
lowing tables are illustrative of the application of 
Ohm’s Law in three successive cases in which the 





















AND SWITCHBOARDS 


21 


current remains constant, the volts constant and 
the resistance constant. The influence of this con¬ 
dition is interesting in each table and shows that 
either amperes, volts or ohms can be calculated 
by knowing the other two, as follows: 

Table I—Amperes = volts — ohms. 

Table II—Volts = amperes X ohms. 

Table III—Ohms = volts -f- amperes. 

Table I. C = E -y R. 


Current Remains Constant. 


Amperes. 

Volts. 

Ohms. 

IO 

IO 

I 

IO 

20 

2 

IO 

3 ° 

3 

IO 

40 

4 

IO 

5 o 

5 


Table II. E = CXR. 


Volts Remain Constant. 


Amperes. 

Volts. 

Ohms. 

IO 

100 

10 

20 

100 

5 

30 

100 

3-333 

40 

100 

2-5 

50 

100 

2.0 


I 
















22 


ELECTRIC-WIRING, DIAGRAMS 


Table III. R = E-yC. 

Ohms Remain Constant. 


Amperes. 

Volts. 

Ohms. 

IO 

100 

IO 

20 

200 

IO 

30 

3 00 

IO 

40 

400 

IO 

5 ° 

5 00 

IO 


In the cases cited E is divided twice, once by R 
and once by C, and R and C are multiplied together. 
So it is easy to remember that the two factors mul¬ 
tiplied together are the two which are respectively 


E 



divided into E to get either C or R. For instance 
E -f- by either C or R = either R or C, and C X R 
= E, which might be represented by the following 
■sketch: 









AND SWITCHBOARDS 


2 3 


The two lower ones multiplied give E (Fig. i) ; 
the upper one, divided by either of the lower, gives 
the remaining character. It is very convenient to 
those unaccustomed to algebraic forms to carry an 
image in the mind as indicated above with the 
method of handling it. 

Drop of Potential.—A fact with which every one 
should be familiar is that it is impossible to trans¬ 
mit power from place to place without a loss. If 
steam is sent through a pipe to run an engine, the 
longer the pipe the greater the loss of power be¬ 
fore the steam is utilized. The smaller the diame¬ 
ter of a pipe the greater the waste of power in trans¬ 
mitting. The same principle applies to wire rope 
transmission, in which a very large percentage of 
power disappears between the points sending and 
receiving it, as in the case of cable car systems, 
passenger elevators, etc. 

A wire conducting electric power is subject to 
the same law, which manifests itself in two ways 
first, the pressure or voltage diminishes; secondly, 
the wire develops heat. The loss of pressure, 
which may be shown by the voltmeter, can be 
readily calculated by Ohm’s Law: 

Drop = amperes X ohms. 

For instance, if the problem were given: what 
is the drop of potential in a line of io ohms resist¬ 
ance carrying a current of io amperes? the answer 
would be 

Drop = io X 10= ioo volts. 


24 


ELECTRIC-WIRING, DIAGRAMS 


Rule.—To calculate the drop in a line multiply 
the amperes by the ohms. 


Table Showing Drop in a Line. 


Size of wire 

No. io B & S. 

Amperes. 

Ohms. 

Drop in volts. 

i ,000 feet 

IO 

I 

10 

2,000 feet 

IO 

2 

20 

3,000 feet 

IO 

3 

30 

4,000 feet 

10 

4 

40 

5,000 feet 

IO 

5 

50 


It is evident from an inspection of the table that 
the drop increases as the resistance or current in¬ 
creases. The loss of power in a line can be dimin¬ 
ished by reducing the current in the line or reduc¬ 
ing the resistance of the line. 

Resistance of Wires.—The resistance of a wire 

i 

depends upon the length of the wire, its diameter 
or cross section, and the metal of which it is com¬ 
posed. Resistance is a native property, such as 
elasticity, ductility, malleability, and depends upon 
the quality or purity of the metal, or the mixture 
composing the alloy, as in the case of german silver 
wire. 

If conductors had no resistance, no power would 
be wasted in transmitting current. In addition, a 
very small voltage would be sufficient to send 
heavy currents through a wire. On account of the 
resistance of a wire being governed by its geomet- 











AND SWITCHBOARDS 


25 


rical dimensions, certain rules have been adopted 
by means of which the resistance of copper wires 
of any length or cross section can be readily cal¬ 
culated. Ihe basis which can be employed is the 
resistance of one foot of copper wire, one one- 
thousandth of an inch in diameter, commonly 
called a milfoot, which has a resistance of a little 
less than 11 ohms. The term mil is employed be¬ 
cause it means a thousandth of an inch, or a thou¬ 
sandth part, and refers in this case to a round 
wire of the diameter above mentioned. If two 
such wires are placed side by side the resistance 
is reduced to one-half, three such wires will reduce 
it to one-third, etc. In other words, a rule may be 
stated as follows: 

Rule. —The resistance of a wire of fixed length 
is inversely proportional to its cross section. 

It is-customary to call a wire of one mil diameter 
a circular mil; a wire of two mils diameter would 
therefore have four circular mils; a wire of three 
mils diameter, nine circular mils, etc. 


Table Showing Relation Between Resistance and Cross 

Section. 


Circular mils. 

Ohms. 

Feet. 

10,000 

1.0 

1,000 

20,000 

•5 

1,000 

30,000 

•3333 

1,000 

40,000 

.2500 

1,000 

50,000 

.2000 

1,000 









26 


ELECTRIC-WIRING, DIAGRAMS 


It is not necessary to show how the resistance 
increases or diminishes as the wire increases or 
diminishes in length, while retaining the same cross 
section in circular mils, because it is obvious that 
a current must move through twice as much re¬ 
sistance in 1,000 feet of wire as 500 feet of the same 
cross section. As a proof of this fact the drop of 
potential with a given current in a fixed cross sec¬ 
tion is just twice as great with twice the length 
of wire, but as drop of potential equals C X R it 
is evident that if the current remains constant the 
drop in both can only increase or double if the 
resistance doubles. 

A simple and practical rule can be deduced from 
these facts which will assume the following form r 

Rule.—The resistance of a wire is proportional 
to its length in feet and inversely proportional to 
its cross section in circular mils. 


Table Showing Relation Between Resistance, Cross 

Section and Length. 


Circular mils. 

Ohms. 

Feet. 

10,400 

IO 

10,000 

5,200 

IO 

5,000 

2,600 

IO 

2,500 

L 3 00 

IO 

1,250 

650 

IO 

625 


Calculating Drop in Volts.— In a single circuit 
the calculation of the drop of pressure is made by 













AND SWITCHBOARDS 


27 


using - Ohms Law in the form previously given: 
I=C X R, or volts drop=amperes X ohms. For 
instance, what is the* loss of volts in a simple cir¬ 
cuit whose resistance is 10 ohms carrying a cur¬ 
rent of 3 amperes? According to the rule drop in 
volts =10 ohms X 3 amperes or 30 volts. If the 
circuit is supplying current to lamps, then the volts 
are no where the current enters; where it leaves 
in the above case, it would be 30 volts less, or only 
80 volts (Fig. 4) ; 30 volts disappearing through 
the effect of the resistance and current. 



Fig. 2. —Lamps in Series, 4 Volts per Lamp. 

In the sketch (Fig. 2) the lamps are shown in 
series with each other; that is, the same current 
passing through one lamp after the other. As two 
amperes pass through each lamp as indicated, and 
as each lamp has two ohms resistance, the drop 
between the ends of each lamp would be 2X2 = 4 
volts. Voltmeters are shown in position across the 
terminals, each giving a reading of four volts, which 













28 


ELECTRIC-WIRING, DIAGRAMS 


is a reading of the drop taking place in the lamp. 
An experiment of this kind can be tried with five 
no volt lamps arranged as shown. Only one volt¬ 
meter is necessary for readings from every lamp. 
When they have all been obtained their sum will 
equal the total voltage applied. 

Series Electric Lighting.—A very practical ex¬ 
ample of the above case of series lighting can be 
found in high tension arc lighting (Fig. 3), so uni- 



DYN. 

O ] 500 V. 


-0— 

50 V. 

-O- 

50 V 

-O— 

50 V. 

-O- 

50 V. 

-O’ 

50 V. 

50 V. 

50 V. 

50 V.~ r 

50 V. ' 

50 V. 

-O— 

-O- 

-O- 

-O- 

-a 


Fig. 3. —High Tension Arc Light System, Series Wiring. 


versally employed in large cities. The lamps are 
placed on street corners as a rule, and extend 
through the city in this manner for a distance of 
several miles. A current of about 10 amperes is 
employed, and each lamp has the equivalent of a 
resistance of 5 ohms. According to these figures 
each lamp will have a drop of 50 volts; therefore, 
if 10 lamps are lit, 500 volts are required, for 20 
lamps 1,000 volts, 40 lamps, 2,000 volts, etc. In a 
lighting system of this kind all wiring is done in 
series, in contradistinction to incandescent light 
wiring, which is done in multiple. The difference 
between the series system and the multiple system 















AND SWITCHBOARDS 


2 9 


of wiring is readily illustrated by a simple sketch 
(Fig. 4 )- 


+o- 

110 VOLTS 


-O 


a AMPERES 


LAMPS Q 
1 A. 


o 

1 A.. 


o 

1 A 


Fig. 4. —Incandescent Light System, Multiple Wiring. 


Multiple Wiring.—In a multiple circuit the cur¬ 
rent divides up; each part of the circuit taking 
current according to its resistance, as shown by 
Ohm’s Law. In the cases mentioned three amperes 
divide up into three separate currents of one am¬ 
pere apiece. The current divides as shown because 
the resistance of each branch will not permit any 
more to pass through. 

Example: The lamps each take 1 ampere at no 
volts, what is the resistance of each lamp? Refer¬ 
ring to the table previously given, it will be seen 
that this is a case where volts and amperes are 
given to find ohms. According to the rule, volts 
divided by amperes gives ohms; therefore no 
divided by 1 gives no ohms per lamp. 

What is Meant by Percentage of Drop.—The 
drop in either a series circuit or a multiple circuit 
is calculated from the amperes and ohms of the cir¬ 
cuit. A very simple formula is employed for the 
purpose of obtaining the size of wire in circular 
mils, in which a stated loss of volts occurs. For in¬ 
stance, if a building is wired for incandescent lights. 











30 


ELECTRIC-WIRING, DIAGRAMS 


it is customary to make an allowance beforehand 
for the drop in volts. This allowance may be 2 
per cent., 3 per cent., etc., as the circumstances 
warrant. If no volts are supplied to the lamps, 
2 per cent, or 2.2 volts will be purposely wasted 
in the circuits before it reaches the lamps. The 
lamps will therefore receive only 107.8 volts. In 
using the formula the number of volts to be dissi¬ 
pated in the circuit under consideration must be 
given. 

Formula: Circular mils = feet of wire X amperes 
in wire X n -r- volts drop in wire. 

Example: Take a circuit 250 feet long carrying 
10 amperes, in which 3 volts drop will be allowed, 
how many circular mils cross section must be sup¬ 
plied for the wire? According to the above, a cir¬ 
cuit with a 250 foot run must have 500 feet of wire, 
giving circular mils equal to 500 X 10X n ^3 = 
: 8,333- The formula is given in symbols in the 
following form : 


C. M.= 


11 X F X 
V 


A 


where F = feet of wire, A = amperes, n is a con¬ 
stant, V = volts drop and C. M. = circular mils. 
The constant 11 is the resistance in ohms of 1 mil 
foot of copper wire. 



AND SWITCHBOARDS 


3* 


Table Showing Effect of Percentage of Drop on Circular 

Mils of Wire Required. 



Formula: 

11 x F x A 

= C. M. 


V 

Amperes. 

Percentage 
of drop. 

Circular 

mils. 

Feet of 
wire. 

Volts drop. 

IO 

I 

100,000 

1,000 

1.1 

. 

2 

50,000 

1,000 

2.2 

IO 

3 

33 >333 

1,000 

3-3 

IO 

4 

25,000 

1,000 

4-5 

IO 

5 

20,000 

1,000 

5-5 


Volts for lighting = no. 

The volts supplied are supposed to be fairly con¬ 
stant ; the amperes may vary according to the num¬ 
ber of lamps burning. The amount of copper is 
well represented by the circular mils in each case 
where the percentage of drop is varied. With 5 
per cent, drop only one-fifth of the copper required 
in the first case is necessary. 

Sizes of Wire and Circular Mils.—The sizes of 
wire are known by reference to the number of cir¬ 
cular mils they represent and vice versa. The num¬ 
ber of circular mils of a round wire may be ob¬ 
tained by squaring the diameter of the wire in mils. 

For instance, a wire one-tenth of an inch in 
diameter is or 100 mils in diameter; the 

square of 100 mils is 100X100=10,000 circular 
mils. 

















3 2 


ELECTRIC-WIRING, DIAGRAMS 


Resistance and Circular Mils.—For practical pur¬ 
poses it is safe to assume n ohms resistance for 
a wire I foot in length and one circular mil in cross 
section. Therefore the resistance of a wire I foot 
long and having two circular mils cross section will 
be one-half of n ohms or 5.5 ohms. On this basis 
fewer circular mils to a wire mean more resistance 
and more circular mils mean less resistance. The 
resistance of wires can be calculated by a simple 
formula which expresses the idea just stated in a 
concise form. 

Formula: Resistance in ohms equals feet of wire 
X II -T- circular mils. 

Example: For instance, what is the resistance 
of 100 feet of wire of 1,000 circular mils? The 
answer is, ohms equals 100 X n -r- 1,000 = 1.1 
ohms. 

From the foregoing it is not a difficult task to 
arrange a table showing the relationship existing 
between the length of a wire, its cross section in 
circular mils and its resistance in ohms. 


AND SWITCHBOARDS 


33 


Table Based Upon the Formula, Showing the Relation 
Between Ohms, Feet of Wire and Circular Mils. 


„ . _ 11 X ft. wire 

Formula: R = ——- - -— 

Circular mils. 


Circular mils. 

Ohms. 

Feet wire. 

1,000 

II.0 

1,000 

2,000 

5-5 

1,000 

3,OOO 

3.666 

1,000 

4,000 

2 -75 

1,000 

5,000 

2.2 

1,000 

10,000 

1.1 

1,000 


With the number of feet of wire constant, the 
resistance is inversely proportional to the circular 
mils. For instance, with C. M. = i,ooo, R=ii 
ohms, but with C. M.= 10,000, R=i.i ohms,, 
showing that with 10 times the cross section the 
•resistance becomes one-tenth. 

Resistance in Multiple. —Calculating the joint re¬ 
sistance of a number of resistances in multiple can 
be accomplished at once if the resistances in mul¬ 
tiple are equal in the first case, or by a simple cal¬ 
culation if the resistances in multiple are unequal 
in the second case. 

Resistances are Equal. —When resistances are in 
multiple and are equal to each other take the resist¬ 
ance of one and divide it by the number of resist¬ 
ances. 

Example: For instance, take a circuit consisting 
3 











34 


ELECTRIC-WIRING, DIAGRAMS 


of 20 lamps in multiple each having a resistance of 
ioo ohms, what is the total resistance? The total 
resistance is equal to the resistance of one lamp, 
which is ioo ohms, divided by the number of lamps, 
.which is ioo -1-20 = 5 ohms. 

Equal Resistances in Multiple. 


Formula: 


resistance of 1 branch 
number of branches. 


Number of resistances. 

Resistance of each. 

Total resistance. 

50 

1,000 ohms 

20 ohms 

40 

800 ohms 

20 ohms 

3 ° 

600 ohms 

20 ohms 

20 

400 ohms 

20 ohms 

10 

200 ohms 

20 ohms 

5 

100 ohms 

20 ohms 


In dealing with incandescent lamps a fact to be 
remembered is that the resistance of the lamp cold 
is much greater than its resistance hot. A 16 cp., 
no volt lamp cold, has a resistance of 450 ohms; 
when it is burning its resistance drops to about 120 
ohms. Therefore if a bank of lamps is measured 
cold, when in multiple, the resistance will be much 
higher than when its total resistance is calculated 
from the volts and amperes required when lighted. 

Resistances are Unequal.—When resistances in 
multiple are unequal a simple calculation is em¬ 
ployed. The rule is as follows: The total resistance 











AND SWITCHBOARDS 


35. 


is equal to the reciprocal of the sum of the recipro¬ 
cals of the resistances. The practical application 
of the rule can be best shown by a case in point. 
Example: What is the resistance of the following 
resistances in multiple: 5, 10, 15 and 20 ohms? 
According to the rule 

R= 1 + (I + lV + fa + -fa)- 

In other words, add the fractions together whose 
numerators are now one, and whose denominators 
are the various resistances in multiple. In the 
above case R = I -f- = §-§ = 2.4 ohms. It will 

be noted that the resistance of a group of unequal 
resistances in multiple is always less than the low¬ 
est resistance of the group. For instance, in the 
case just given the total resistance 2.4 ohms is less 
than the lowest resistance of the group, which is 
5 ohms. Adding up the reciprocals of the resist¬ 
ances and inverting the fraction explains the above¬ 
process. To illustrate, take the resistances 1, 2, 3, 
4 and 5 ohms in multiple, what is their total resist¬ 
ance? If the reciprocals are added together the 
fraction obtained is -^y-. Inverting this fraction 
gives the answer T W = .438 ohm. If the various 
resistances in multiple are fractional they must be 
treated in the same manner, although the reciprocal 
of fractions such as \ is 2, J is 4, etc. 


36 ELECTRIC-WIRING, DIAGRAMS 


Unequal Resistances in Multiple. 


Formula: R = 1-5- ( ——-—L- r + ——-——- 7- + etc. ^ 

\R of 1st branch R of 2d branch / 


Resistance in 



Total 

multiple. 

Sum of reciprocals of resistances. 

resistance. 

Ohms. 



Ohms. 

1,2,3 

i+i + 5 ... 

JJL 

•545 

U 2, 3, 4 

i+*+*+i . 

2.5. 

•z 

.480 

1,2, 3, 4, 5 

+ . 

lat 

60 

• 43 8 

10, 20, 30, 40, 50, 60 

2 , 4 , b l 

A + A 4 - A + A 4 - A + A - 

L : L 

b l) 0 

4.081 

2 +4 +3 +8 . 

T 7 

.0588 

. 1 . X _L _L. JL_ 
lo, 2<J> ao, 40, fid 

10 + 20 +30 +40 + 50. 

15 ° 

.00666 


Examples of Drop of Potential.—The drop of 
pressure in a circuit is not the only instance of a 
waste of energy met with in actual practice. The 
dynamo is also affected in its most vital part by 
the passage of a current through conductors, which 
while performing the function of generating elec¬ 
tromotive force, are at the same time acting in the 
capacity of conductors which possess resistance 
and develop drop in the operating machine. The 
part referred to is the armature, and allowance 
must be made for this deficiency when the dynamo 
is running at one-quarter, one-half, or full load. 
Take the case of a 100-light generator; its amperes 
at no volts pressure are approximately 50, if the 
armature resistance is one-tenth of an ohm, the 
drop at the indicated points of load will be re¬ 
spectively : 



















AND SWITCHBOARDS 


37 


Drop at one-quarter load =12.5 amperes X .1 
ohm = 1.25 volts. 

Drop at one-half load —25.0 amperes X .1 ohm 
= 2.50 volts. - 

Drop at full load = 50.0 amperes X .1 = 5.00 
volts. 

It is but natural to suppose that this will have 
its effect upon the candle power of the lamps. 
At full load a no volt lamp will receive only 105 
volts, which will mean a great depreciation in illu¬ 
minating power, sufficient perhaps to make electric 
lighting on this basis an expensive luxury. 

A modern dynamo is built to automatically build 
up its electromotive force as the load increases. 
Such dynamos are called compound wound dyna¬ 
mos, and are of immense service in comparison 
with the older type, in which regulation was only 
obtained by hand. 

In an electric light system the following items 
’must be considered: 

Drop in the armature. 

“ “ switchboard. 

“ “ mains. 

“ “ feeders. 

“ “ branches. 

The drop in the armature need not be considered 
as part of the drop in a wiring system, although 
indirectly it contributes to the difficulty of solving 
special problems. Loose joints and poor connec¬ 
tions were a source of great danger and loss of 
power, in wiring of the past decade, but the severe 



3 § 


ELECTRIC-WIRING, DIAGRAMS 


inspection of to-day has obliterated such evils. It 
is within the province of a treatise on wiring to em¬ 
brace all questions relating to the passage of the 
•current after leaving the dynamo. As the ultimate 
object of wiring is to limit the waste of power and * 
the amount of copper employed, as well as to se¬ 
cure good candle power for the lamps, data on all 
three is of the utmost importance in the considera¬ 
tion of wiring for power and distribution of power. 

Calculation of Power.—Power is calculated in 
watts. Watts are equal to the product of volts by 
amperes. If either the volts or amperes of a cir¬ 
cuit are increased or diminished, the power will be 
correspondingly increased or diminished. For in¬ 
stance, what is the power obtained from no volts 
and 25 amperes? The answer is 25 X 110 = 2,750 
watts. The watts can be still further transformed 
in horse-power by dividing them by 746. There are 
746 watts in a horse-power, therefore 2,750 watts 
-T- 746 = 3.68 horse-power, generally denoted by the 
symbols hp. 


Power Table, Showing Relationship Between Watts, Volts 

and Amperes. 


Volts. 

Amperes. 

Watts. 

Horse-power. 

Kilowatts. 

1,000 

IOO 

100,000 

134.0 

100 

500 

200 

100,000 

134.0 

100 

250 

400 

100,000 

134.0 

100 

125 

800 

100,000 

134.O 

100 














AND SWITCHBOARDS 


39' 


Kilowatt.—The kilowatt simply means 1,000 
watts, and roughly represents ij hp. Manufactur¬ 
ers rate their dynamos on this basis instead of 
speaking of their horse-power or lighting capacity 
in lamps. The power consumed by an incandescent 
lamp varies from 3 to 4 watts per candle power. 
A 16 cp. lamp takes from 48 to 64 watts. A horse¬ 
power would supply power for from 11 to 15 lamps,, 
depending upon their rating per candle power. 


40 


ELECTRIC-WIRING, DIAGRAMS 


CHAPTER II 

CARRYING CAPACITY OF WIRES.—EFFECTS OF HEAT UPON 
RESISTANCE.—ALLOWANCE FOR HEAT.—A SIMPLE ELEC¬ 
TRIC LIGHT CIRCUIT.—WIRE OF A IO LAMP CIRCUIT 
WITH DROP ANALYZED.—THE WIEDEMANN SYSTEM OF 
LIGHTING AND ITS DEFECTS.—THE WIRING TABLE.— 
HOW TO PREPARE A TABLE OF SIZES AND CIRCULAR 
MILS.—EXAMPLES OF THE APPLICATION OF THE WIRING 
TABLE AND FORMULA.—CALCULATION OF THE DROP 
PER 1,000 FEET PER AMPERE. 

Carrying Capacity of Wires.—If the drop of po¬ 
tential in electric light wires was the only thing to 
be feared, it would be a matter of concern only to 
the consumer of electricity and the power company. 
The candle power would not be up to the standard, 
and the waste of power in the conducting wires 
would represent a heavy percentage of the cost of 
transmission. But this is not all, and the matter 
is of importance to the community as well, because 
when excessive energy is wasted in the conducting 
wires, not only does it become manifest as drop of 
pressure but as heat. The danger of an unusual 
rise of temperature in the wires is removed by the 
limitations imposed on contractors in the United 
States. These may be found in the National Elec¬ 
trical Code of the Fire Underwriters. 


AND SWITCHBOARDS 


41 


Rubber Covered Wires.—The wire employed in 
electric wiring is protected by a rubber covering, 
the name generally applied being “ rubber covered 
wires.” A rise in temperature of 30 degrees F. is 
allowed in such wires, and as this means an in¬ 
crease in resistance and therefore an increase in 
drop, the following table is given for the purpose 
of illustrating this fact: 

Effect of Temperature Upon Resistance of Wires and Drop 

of Pressure. 


1,000 feet No. 10 B. & S. = 1 ohm. 


Current. 

Increase in 
temperature. 

Increase in 
resistance. 

Increase 
in drop. 

IO 

10 degs. F. 

.022 ohm 

.22 volts 

IO 

20 degs. F. 

.044 ohm 

.44 volts 

IO 

30 degs. F. 

.066 ohm 

.66 volts 

IO 

40 degs. F. 

.088 ohm 

.88 volts 

IO 

50 degs. F. 

.110 ohm 

1.10 volts 

IO 

75 degs. F. 

.165 ohm 

1.65 volts 

IO 

100 degs. F. 

.220 ohm 

2.20 volts 


This table is based upon the increase in resist¬ 
ance in a copper wire due to an increase in tem¬ 
perature. A rise of 1 degree F. means an increase 
in resistance of .0022 per cent, (nearly J of 1 per 
cent.). The formula employed is as follows: 

Formula: Resistance at an increased temperature 
— resistance of wire in ohms X .0022 X rise in de¬ 
greed Fahrenheit + the resistance of the wire. 















42 


ELECTRIC-WIRING, DIAGRAMS 


To illustrate, supposing a wire has 5 ohms re¬ 
sistance and the rise in temperature is 20 degrees 
F., what is the resistance? The resistance = 5 
X .0022 X 20 + 5 = 5.22 ohms. The resistance of 
wires of other metals than copper can be calculated 
by the same formula provided the constant is ob¬ 
tained from the table of constants given under the 
heading of “ Temperature Coefficients.” 

TEMPERATURE COEFFICIENTS. 


Percentage Increase of Resistance per i Degree Fahrenheit. 


Percentage. 

Metal. 

30 degrees F. 

.002156 

Copper. 

.06468 

.002517 

Iron. 

•Q 755 1 

.OOO244 

German-silver. 

.00732 

.OOI372 

Platinum. 

.O4II6 

.002167 

Aluminum. 

.065OI 


Calculation of a Simple Circuit.—Because the 
lengths of wire connected to each lamp are differ¬ 
ent, the resistance of each circuit and therefore the 
drop of pressure is different. In the circuit illus¬ 
trated, the drop of each lamp becomes greater the 
further it is removed from the source of the supply 
of power: 

For instance (Fig. 5), lamp No. 1 has 100+ 100 
= 200 feet of wire connected to it, and lamp No. 
10 has 200 -j- 180-f- 180 = 560 feet of wire in its 
circuit. The other lamps have lengths of wire in 
their circuits lying between 200 feet and 560* feet. 














AND SWITCHBOARDS 


43 


For this reason it is evident that the resistance in 
circuit with each lamp is different and therefore the 


h-100 FT. NO. 10 B. & 6.-V 

+0---- 

-C20> 

<■20^ 

<20> 


SOURCE OF SUPPLY 











© 00©©©©©©0 


AMPERES 10 

LAMPS 1 AMPERE EACH 

)-- 


















100 FT. NO. 10 B. <S, S.->j 


Fig. 5.—Analysis of a 10 Lamp Circuit. 

drop is unequal throughout the line. Using No. 10 
wire and allowing one ampere per lamp gives the 
following data: 


Circuit or 10 Lamps Taking i Ampere Apiece. Size Wire, 

No. 10 B. & S. 


Position of lamp. 

Feet of wire. 

Resistance. Ohm. 

No. 1 

200 

.200 

No. 2 

240 

.240 

No. 3 

280 

.280 

No. 4 

320 

.320 

No. 5 

360 

.360 

No. 6 

400 

.400 

No. 7 

440 

.440 

No. 8 

480 

.480 

No. 9 

5 2 ° 

.52° 

No. 10 

560 

.560 


Current in the Wire.— the drop in the wire can¬ 
not be calculated by merely multiplying the main 





































44 


ELECTRIC-WIRING, DIAGRAMS 


current by the various resistances of the various 
circuits given above. An examination of the circuit 
will show that the connecting wires of lamp No. I 
carry io amperes, while the connecting wires of 
lamp No. 2 carry io amperes and 9 amperes. This 
unequal distribution of current in the connecting 
wires which lead up to all of the lamps and the 
difference in drop in each lamp is shown in the 
following table: 


Distribution of Current in Connecting Wires of a Simple 

10 Lamp Circuit. 


Position of wire. 

Current 
in wire. 

Resistance Drop in 
of wire. volts. 

Between source and lamp No. 1.. 

Amperes. 

IO 

Ohm. 

.200 

2.000 

Between No. 1 and No. 2. 

9 

.040 

.360 

Between No. 2 and No. 3. 

8 

.040 

.320 

Between No. 3 and No. 4. 

7 

.040 

.280 

Between No. 4 and No. q. 

6 

.040 

.240 

Between No. 5 and No. 6. 

5 

.040 

.200 

Between No. 6 and No. 7. 

4 

.040 

.160 

Between No. 7 and No. 8. 

3 

.040 

.120 

Between No. 8 and No. 9 . 

2 

.040 

.080 

Between No. 9 and No. 10. 

1 

.040 

.040 


The last column of this table shows the drop 
due to the current and connecting wires of each 
lamp, but it does not show the total drop of the 
lamp. To illustrate, the first lamp has a drop of 
2 volts, because its connecting wires carry the full 

























AND SWITCHBOARDS 


45 


io amperes and have a resistance of .2 ohm. The 
second lamp, however, is different; its drop is 
greater, because it not only meets with the drop of 
the first lamp, but that of its connecting wires 
lying between lamps No. 1 and 2, equal to .36 volt. 
Lamp No. 2 therefore has a drop equal to 2.36 
volts, and lamp No. 3 will have a drop equal to 
lamp No. 2 plus the additional drop it experiences 
in its connecting wires lying between lamps No. 2 
and No. 3, amounting to .32 volt, or a total of 2.36 
-f- .32 = 2.68 volts drop for lamp No. 3. 


Drop of Each Lamp in a Simple io Lamp Circuit, Current 
10 Amperes. Size of Wire, No. io B. & S. 


No. of 
lamp. 

Drop from source to lamp. 

Total 
drop in 
volts. 

I 

Volts. 

2.00. 

2.000 

2 

2.00 -f-.26. 

2.360 

2.680 

3 

4 

2.00 4 - . 36 -f- .72 . 

2.00 + .36 + .32 + .28. 

2.960 

5 

2.00 4- .36 + .32 -f .28 + .24. 

3. IO ° 

6 

2.00 4- .36 4- .32 -f- .28 4- .24 4- .20. 

3.400 

7 

2.00 4- .36 4- .32 4- .28 4- .24 4- .20 + .16. 

3 - 56 o 

8 

2.00 + .36 4 - .32 4 - .28 4 - -24 4 -.20 4 -.l 64 ~.I 2 . 

3.680 

9 

2.00 4 - .36 4 - .32 4 - .28 4 - .24 4 - .20 4 - .16 4 - .12 4 - .08. 

3.760 

10 

t 1 ■ ■ 

2.00 4* .36 4- .32 4- .28 4- .24 4- -2o 4- .16 4- .12 4- .08 4- .04 

3.800 


It is of the utmost importance to carefully follow 
the items given in this table and their relation to 
the main facts. The table shows that in any cir¬ 
cuit of the character shown in the illustration the 
drop increases from the source to the last lamp. 


















46 


ELECTRIC-WIRING, DIAGRAMS 


Lamp No. i has a drop of 2 volts, lamp No. 10 a 
drop of 3.8 volts, and between these two occur in¬ 
creases in drop, due to the causes above specified. 

The purpose in view in making an analysis of 
wiring is to find the best methods to employ in 
laying out the circuits, for the purpose of keeping 
the drop as uniform as possible among the lamps. 
This task can only be accomplished intelligently 
and therefore economically, for the problem is as 
much commercial as scientific, by following cer¬ 
tain general principles in mapping out the most 
important circuits. 

The Wiedemann System.—The purpose of the 
Wiedemann system (Fig. 6) was to connect each 



-ar- 0 + 9 AMPERES -O-*-—- 

JOOO_FT.__IO_B._A_S;_^ 11Q V0LTS 

Fig. 6.—Wiedemann System of Wiring. 


lamp in the system with an equal length of wire. 
By this means every lamp represented individually 
a circuit of equal resistance, and it was believed 
that the drop of each lamp would be alike. 

By following the length of circuit through each 
lamp in the sketch it will be seen that each lamp 













AND SWITCHBOARDS 


47 


is supplied with current through 2,300 feet of No. 
10 wire. Take lamp No. 1 for instance, starting 
from the positive pole the current passes through 
1,000 feet of wire, then through the lamp, then 
through B, D, F, H, J, L, N, P (which are the 
connecting wires between lamp and lamp on one 
side of the circuit of 100 feet apiece) and finally 
through the indicated 500 feet of terminal wire. 
The total length met with for lamp No. 1 is there¬ 
fore 1,000 feet + 800 feet + 500 feet = 2,300 feet 
total. Tracing the circuit through lamp No. 2 will 
give 1,000 feet + A + D, F, H, J, L, N, P + 500 
feet = 1,000 + 100 + 700 -f- 500 = 2,300 feet for 
lamp No. 2. Following the circuit through for each 
lamp will show exactly the same length of wire 
connected to each one. If there is the same length 
of the same size of wire connected to each lamp, 
the resistance in circuit with each lamp must be 
the same. The question now arising is this: Will 
the lamps have equal drop and therefore burn with 
equal candle power, or is the drop in the circuit 
of each lamp different? This question can be best 
answered by an investigation of the drop met with 
in the circuit of each lamp. To discover the drop 
in the circuit of each lamp, the resistance and cur¬ 
rent must be known. In the sketch the resistance 
is known, so the problem is reduced down to a 
statement of the number of amperes in each part 
of the circuit of each lamp. 

Amperes in Lamp Circuits.—To find the am¬ 
peres in each lamp circuit refer to the sketch be- 


48 


ELECTRIC-WIRING, DIAGRAMS 


ginning with lamp No. i. Because every lamp has 
the two terminals of the circuit, respectively 1,000 
feet and 500 feet to consider alike, they will be 
left out of consideration for the present a!nd par¬ 
ticular attention paid to the current in the con¬ 
necting wires met with in the circuit of each lamp. 
Following the 9 amperes along from the -f- pole it 
is seen that 1 ampere passes through lamp No. 1 
and enters connecting wire B, leaving 8 amperes 
to pass through connecting wire A. Another am¬ 
pere passes through lamp No. 2 and enters con- 


Connecting wire. 

Amperes. 

Drop in volts. 

Positive wire. 



A 

8 

.1 X 8 = .8 

C 

7 

•1 x 7 = .7 

E 

6 

.1 X 6 = .6 

G 

5 

•1 X 5 = .5 

I 

4 

.1X4 = 4 

K 

3 

•I X 3 = .3 

M 

2 

.1 X 2 = .2 

O 

1 

.1 X I = .1 

Negative wire. 



B 

1 

.1 X 1 = .1 

D 

2 

.1 X 2 = .2 

F 

3 

- 1 x 3 = .3 

H 

4 

.1 X 4 = .4 

J 

5 

•I x 5 = .5 

L 

6 

.1 X 6 = .6 

N 

7 

■1x7 = 7 

P 

8 

.1 X 8 = .8 














AND SWITCHBOARDS 


49 


necting wire D, returning with the ampere from 
connecting wire B. The following table will clearly 
show the distribution of current in the connecting 
wire of the circuit. 

It is now a simple task to discover the drop met 
with in the circuit of each lamp. For instance, 
lamp No. i meets with a drop of .1 volt in B, .2 
volt in D, and in F, H, J, L, N, and P respectively, 
a drop of .3 T - *4 -f" *5 "T ~f~ *7 + >8 volt or a total 
of 3.6 volts. Lamp No. 1 has its circuit through 
B, D, F, H, J, L, N, and P; lamp No. 2 its circuit 
through A, D, F, H, J, L, N, and P, and lamps Nos. 
3, 4, 5, etc., as shown in the following table: 


No. of 
lamp. 

Circuit of lamp. 

1 

B, D, F, H, J, L, N, P — 

2 

A,D, F,H, J, L, N, P... 

3 

A, C, F, H, J, L, N, P... 

4 

A, C, E, H, J, L, N, P... 

5 

A, C, E, G, J, L, N, P... 

6 

A, C, E, G, I, L, N, P... 

7 

A, C, E, G, I, K, N, P... 

8 

A, C, E, G, I, K, M, P — 

9 

A, C,E, G, I, K, M, O .. 


Total drop of lamp. 


.1 + 

2 + 

3 + 

4 + 

5 + 

6 + 

7 +*8= 

= 3.6 

•8 + 

2 + 

3 + 

4 + 

5 + 

6 + 

7 +-8= 

=4-3 

.8 + 

7 + 

3 + 

4 + 

5 + 

6 + 

7 +-8= 

-4 , 8 

•8 + 

7 + 

6 + 

4 + 

5 + 

6 + 

7 +-8= 

r 5- x 

•8 + 

7 + 

6 + 

5 + 

5 + 

6 + 

7 +-8= 

r 5 .2 

•8 + 

7 + 

6 + 

5 + 

4 + 

6 + 

7 +.8r 

-5-i 

•8 + 

7 + 

6 + 

5 + 

4 + 

3 + 

7 +-8= 

-4.8 

•8 + 

7 + 

6 + 

5 4* 

4 + 

3 + 

2 +.8= 

= 4-3 

.8 + 

7 + 

6 + 

5 + 

4 + 

3 + 

2+.I = 

=3-6 


According to the above data lamp No. 5 has the 
greatest drop and will therefore burn the dimmest. 
Its loss is 5.2 volts, then come lamps Nos. 4 and 
6 with a drop of 5.1 volts apiece, then lamps Nos. 
3 and 7 with an equal drop of 4.8 volts, lamps Nos. 
2 and 8 with 4.3 volts drop and finally lamps 
4 
















50 


ELECTRIC-WIRING, DIAGRAMS 


Nos. i and 9 with equivalent drops in pressure 
of 3.6 volts. The middle lamps burn dimly, the 
ones on each side a little brighter, the lamps on 
each side of these a little brighter, etc. If the 
•number of lamps arranged as shown in the sketch 
are even, the two middle ones will burn equally 
bright, the candle power increasing from these 
two in pairs equally to the two ends of the circuit. 
An experiment with a bank of 20 lamps connected 
up as shown on a no volt circuit will demonstrate 
the fall of candle power from the ends to the 
middle of the circuit. It is therefore evident that 
in the Wiedemann system although each lamp is 
in circuit with the same amount of resistance, be¬ 
cause the current is different in the connecting 
wires the drop of each lamp is different from its 
neighbor as shown. 

The Wiring Table.—The manufacture of wire for 
electric light and power purposes has meant the 
utilization of a variety of wire gauges; among 
which, the most important is the Brown and 
Sharpe, commonly indicated as the B. & S. gauge. 
These gauges differ from each other in their sizes 
:and the circular mils corresponding to these sizes. 
If the B. & S. gauge is taken as the standard, all 
the sizes of wire in this particular gauge can be 
shown to arbitrarily arise from a consideration of 
the No. 10 size. This has approximately 10,400 
circular mils cross-section and a resistance of about 
1 ohm per 1,000 feet. 

An examination of the B. & S. table will show 


AND SWITCHBOARDS 


5i 


the following interesting facts, of which practical 
use may be made in the development of a table 
for ready reference that will be almost identical 
with the wire manufacturers. In the first place,, 
every three sizes of wire mean that the circular 
mils have either doubled or halved. For instance,, 
a No. io wire, B. & S., has 10,380 circular mils; if 
a No. 7, which is three sizes larger, is compared, 
it is found to possess twice as many circular mils 
or 20,760. On the other hand, comparing a No. 
13 wire, which is three sizes smaller, only one-half 
the circular mils, or 5,190, are found. The same 
process can be carried on with respect to No. 10 
B. & S., for every size given in the regular wire 
table, such as Nos. 13, 16, 19, 22, etc., as well as 
Nos. 7, 4, 1,000, etc. 

It is well to know that the numbers correspond¬ 
ing to the different sizes of wire do not correspond 
numerically to the circular mils they represent. 
The circular mils of a wire diminish according to 
the table as the number of the wire increases. A 
No. o wire has more circular mils than a No. 10; 
or a No. 13 wire has less circular mils than a No. 
10, etc. These facts are best understood by a care¬ 
ful survey of the wire table as printed by the well- 
known manufacturers: 


5 2 


ELECTRIC-WIRING, DIAGRAMS 


Gauge No. B. & S. 

Diameter in inches. 

Cross section. 
Circular mils. 

4-0 

0.4600 

211,600 

3-0 

0.4096 

167,800 

2 —0 

0.3648 

1 3 3 , 1 00 

I —0 

O.3249 

105,500 

1 

0.2893 

83,690 

2 

0.2576 

66,370 

3 

O.2294 

5 2 > 6 3 ° 

4 

O.2043 

41,740 

5 

0.1819 

33 TOO 

6 

0.1620 

26,250 

7 

O.1443 

20,820 

8 

0.1285 

16,510 

9 

0.1144 

I 3 >° 9 ° 

10 

0.1019 

10,380 

j0 


The above figures give all sizes of wire as indi¬ 
cated from No. io B. & S. to No. 4 — 0, in other 
words, all of the larger sizes. According to the 
empirical rule just given No. 7 wire must have 
twice the circular mils of No. 10; No. 4 twice the 
circular mils of No. 7, etc., as shown below: 


No. 10... 

...10,380 C. 

M., according 1 

to table. 


No. 7... 

.. .twice No. 

10 B. 

&S., 

or 

20,760 

C. M. 

No. 4... 

.. .twice No. 

7 B. 

&S., 

or 

41,520 

C. M. 

No. 1... 

.. .twice No. 

4 B. 

&S., 

or 

83,040 

C. M. 

No. 3—0 

.. .twice No. 

1 B. 

&s., 

or : 

166,080 

C. M. 


The intermediate sizes, such as the sizes that lie 
between No. 10 and No. 7, No. 7 and No. 4, etc., 
















AND SWITCHBOARDS 


53 


are found as follows: The difference in circular 
mils between No. io and No. 7 is 10,380; these are 
divided up equally between the three sizes, namely. 
Nos. 9, 8 and No. 7 gauge. Dividing this differ¬ 
ence into three parts gives 10,380 -f- 3 = 3,460 cir¬ 
cular mils. If 3,460 circular mils are added to No. 
10, No. 9 is obtained as shown below: 

No. 10 = 10,380 circular mils = 10,380 

No. 9 = 10,380 + 3,460 = 13,840 

No. 8 = 10,380 + (2 X 3,460) = 17,300 

No. 7 = 10,380 + (3 X 3,460) = 20,760 

This process must be followed out in arriving 
at the size of wire if the circular mils are given, 
or if a table is to be developed for practical pur¬ 
poses. The circular mils obtained by this method 
are such that they will show clearly the size re¬ 
quired. A comparison of the circular mils of the 
manufacturers’ table and the above circular mils 
will demonstrate this fact. 


Regular wire table. 

Calculated sizes. 

Difference. 

No. 10.. . 

...10,380 

No. 10... 

.. .10,380 

O 

No. 9... 

...13,090 

No. 9... 

...13,840 • 

75 ° 

No. 8... 

...16,510 

No. 8... 

...17,300 

790 

No. 7... 

_20,820 

No. 7... 

_20,760 

60 


In spite of apparently large differences in area 
as shown by Nos. 9 and 8, between the regular 

















54 


ELECTRIC-WIRING, DIAGRAMS 


table and the calculated sizes, the nearest sizes 
manufactured to those calculated are Nos. 9 and 8 
of the regular table. This removes any doubt of 
the practicability of the method. The other half of 
the table giving the sizes from No. 10 to No. 16, 
which are the lesser sizes, is subject to exactly the 
same rules: 


Gauge No. 

B. & S. 

Diameter in inches. 

Cross section in cir¬ 
cular mils. 

IO 

0.1019 

10,380 

II 

0.09074 

8,324 

12 

0.08081 

6,530 

13 

0.07196 

5 T 7 8 

14 

0.06408 

4,107 

15 

0.05707 

3> 2 57 

16 

0.05082 

2 > 5 8 3 


A point of difference arises, however, when size 
No. 13 is to be obtained from No. 10; in other 
words, when passing from a larger to a smaller 
size of wire. In this case the difference is to be 
subtracted instead of added. This means the recol¬ 
lection of the following rule: 

Rule.—In passing from smaller to larger sizes 
of wire add the difference; in passing from larger 
to smaller sizes of wire subtract the difference. 

To illustrate this fact, No. 10 wire differs from 
No. 13 wire as 10,380 circular mils differ from 5,190 
■circular mils. This means that each intermediate 
size from No. 10 to No. 13 varies one-third of 5,190 










AND SWITCHBOARDS 


55 

circular mils or 1,730 circular mils from its neigh¬ 
bor as indicated below: 


Size wire. 

Circular mils. 

IO 

10,380 = 10,380 

II 

10,380 - a X 5,190) = 8,650 

12 

10,380 - (f X 5,190) = 6,920 


10,380 - (| X 5,190) = 5,190 


Although the size and circular mils are obtained 
very readily by a little practice with the above- 
method, it is very important to know how to get 
the resistances as well. This is not any more 
difficult than the preceding, assuming a resistance- 
of 1 ohm per 1,000 feet of No. 10 wire. As the re¬ 
sistance of a wire is inversely proportional to its- 
cross-section in circular mils, a No. 13 wire which 
has 5,190 circular mils or one-half as much cross- 
section as a No. 10 would have twice the resist¬ 
ance per 1,000 feet or 2 ohms. A table can be 
constructed based on this principle as follows: 


Ratio of C. M. 

Size of wire. 

Circular mils. 

Resistance in 
ohms. 

I 

IO 

10,380 

I. OOOO 

2 

7 

20,760 

.5000 

4 

4 

4 T 5 2 ° 

.2500 

8 

1 

83,040 

.1250 

16 

3 -o 

166,080 

.0625 

















56 ELECTRIC-WIRING, DIAGRAMS 

The intermediate resistances are obtained by 
the same rule as that giving the circular mils. 
For instance, the resistance of a No. 9 and 8 is 
obtained by subtracting one-third of one-half of 
the difference in passing from the smaller sizes to 
the larger, and in adding one-third of one-half the 
difference in passing from the larger sizes to the 
smaller. 

If No. 10 has 1 ohm per 1,000 feet, then No. 7 
lias .5 ohm per 1,000 feet and the difference is .5 
ohm. This difference is divided by 3, giving .1666 
ohm. In other words, the subtraction of .1666 ohm 
from No. 10 will give No. 9; subtracting .1666 
ohm from No. 9 will give No. 8, etc., as indicated 
below: 


Size wire. 

Resistance per 1,000 feet. 

IO 

1 = 1.0000 

9 

I — .1666 = .8334 

8 

1 — (2 X .1666) = .6668 

7 

1 - (3 X .1666) = .5000 


For sizes which run the other way, that is, from 
a larger to a smaller size, addition is necessary. 
The following figures are correct in passing from 
No. 10 to No. 13: 







AND SWITCHBOARDS 


57 


Size wire. 

Resistance per 1,000 feet. 

IO 

1. 0000 = 1. 0000 

II 

l + (i x 1) = 1.3333 

12 

1 + (} X 1) = 1.6666 

13 

1 + (t X 1) = 2.0000 


By carefully following the method as described, 
entire independence of the regular wire table re¬ 
sults. It is possible to arrive at the size, circular 
mils and resistance of any wire by a short calcu¬ 
lation or a mental estimate, which not only saves 
time, but is an immense advantage to those em¬ 
ploying such principles as given as a means of daily 
livelihood. A few examples will show the appli¬ 
cation and value of the process in a simple wiring 
system: 

Example.—What is the size and circular mils of 
the wire required to conduct 30 amperes over a 
350 foot run (Fig. 7) at a drop of 2 per cent., the 
pressure being no volts? 

The data is as follows: 


Drop. 2.2 volts. 

Length of wire. 7 00 ^ ee h 

Amperes. 3 ° 


According to the formula: 

700 X 30 X 11 


C. M. = 


2.2 


= 105,000. 











58 ELECTRIC-WIRING, DIAGRAMS 

The practical question arising is this, what is 
the resistance per 1,000 feet and size corresponding 
to the answer? This is the method, starting from 
No. io B. & S.: 



Fig. 7.—Estimating Circular Mils and Size of Wire Without Wire 

Table for Reference. 


No. 10. 10,380 i ohm per 1,000 feet. 

No. 7. 20,760 .5 ohm per 1,000 feet. 

No. 4. 41,520 .250 ohm per 1,000 feet. 

No. 1- 83,040 .125 ohm per 1,000 feet. 

No. 3 —o.166,080 .0625 ohm per 1,000 feet. 




















AND SWITCHBOARDS 


59 


It is evidently between No. i and No. ooo, and 
if one-third of the difference is added, or 27,680 
circular mils, 110,720 are obtained corresponding 
to a No. o wire. The resistance of this size is .125 
ohm minus one-third of the difference in resist¬ 
ance between the two sizes. The resistance of 
1,000 feet of No. o wire is therefore approximately 
.1042 ohm. If 1,000 feet = .1042 ohm, then 700 
feet —- .073 ohm. 

Applying the law that E = C X R to check the 
answer, the drop is found to be 30 amperes X -073 
ohm = 2.19 volts. 

In the above, the nearest size manufactured is 
No. o, and this size would have to be employed 
even though a difference of 5,000 circular mils 
existed. 



Example.—A power line is being run a distance 
of 500 feet (Fig. 8) to a 220 volt motor, taking 50 
amperes with a drop of 5 per cent., what is the size 
of wire, etc.? 


C. M. = 


1,000 X 50 X II 


50,000. 


No. 4 = 41,520. 
No. 3 = 55.360. 


II 





6o 


ELECTRIC-WIRING, DIAGRAMS 


The nearest size is No. 3 B. & S. and the resist¬ 
ance is approximately .209 ohm per 1,000 feet. The 
drop is therefore .209X50=10.45 volts, a little 
short, but still to the advantage of the contractor. 
A table may be prepared which will save a great 
deal of time if properly used, in which the drop in 
volts per ampere per 1,000 feet is given as follows: 


Size wire. 

Drop in volts per 1,000 feet per ampere. 

IO 

I. OOOO 

7 

.5000 

4 

. .2500 

1 

.1250 

3 -o 

.0625 

Taking it the other way toward the smaller sizes 

the figures are in 

near approximation. 

Size wire. 

Drop in volts per 1,000 feet per ampere. 

IO 

I.OOOO 

r 3 

2.0000 

16 

4.0000 


The intermediate sizes and the drop correspond¬ 
ing to them on this basis would give a complete 
table as follows: 













AND SWITCHBOARDS 


61 


Size wire in 
B. & S. gauge. 

Volts drop per 1,000 
feet per ampere. 

Size wire in 
B. &S. gauge. 

Volts drop per 1,000 
feet per ampere. 

4-0 

•° 5 2 3 

6 

.4166 

3-0 

.0625 

7 

.5000 

2 — 0 

• o8 33 

8 

.6666 

I—0 

.1041 

9 

• 8 333 

1 

.1250 

10 

1.0000 

2 

.1666 

11 

1 *3333 

3 

.2082 

12 

1.6666 

4 

.2500 

J 3 

2.0000 

5 

•3333 

14 

2.6666 


Any number of simple problems in wiring can 
be worked out by means of this table, such as the 
following: If a circuit is to be installed to lose 
io volts per 1,000 feet, carrying 30 amperes and 
a total drop of 50 volts, what is its size and length? 

The answer would be 5,000 feet of No. 5 B. & S.; 
because a loss of 10 volts per 1,000 feet, with 30 
amperes, means a loss of .3333 of a volt per am¬ 
pere per 1,000 feet, corresponding to the size given 
above. 

The sketch (Fig. 9) shows the general idea dia- 


tCKHM. 

"A 


<-4- 


** , 
fcr" ±2. 


f.. 


<-++- 


1000 FT. NO. 10 
> 

"^000 ■>< " 7 

-> 


AOOff ».’’ 4 



16000 >> >> 000 


DROP 

1 VOLT 

PER 

AMPERE 

9 » 

1 » 

r» 

V 

»» 


ir 

11 

» » 

9 9 




, I 1 > > • • > 


WEIGHTS 

1 

4 

16 

64. 

““256 


Fig. 9.—Relative Lengths and Weights of Wire of Equal 

Resistance. 























62 


ELECTRIC-WIRING, DIAGRAMS 


grammatically, also the relative weights of copper. 
This last item is of immense importance in con¬ 
nection with the drop, because in some cases 
where but little drop of voltage is very desirable 
the cost is prohibitive. The weight of copper re¬ 
quired to wire a building at 2 per cent, drop is 
exactly twice the amount required to wire a build¬ 
ing at 4 per cent. drop. The saving in copper, by 
using a higher pressure, is apparent from the 
following figures: 


Distance 500 Feet Watts = 10,000, Drop 5 Per Cent. 


Size. 

Volts. 

Amperes. 

Circular 

mils. 

Relative weight 
of copper. 

4 — 0 

100 

IOO 

211,600 

3 2 

I — O 

200 

5 ° 

105,800 

16 

3 

400 

2 5 

5 2 > 9 °° 

8 

6 

800 

! 2*5 

26,450 

4 

9 

1600 

6.25 

T 3> 22 5 

2 

12 

3200 

3- I2 5 

6,612 

I 


This relates more particularly to power trans¬ 
mission but is very instructive in showing how the 
choice of wire, as regards its size, is greatly de¬ 
pendent upon the policy pursued in planning the 
installation. 














AND SWITCHBOARDS 


63 


CHAPTER III 

ELEMENTS OF A WIRING SYSTEM.—MEANING OF MAINS, 
FEEDERS, BRANCHES.—PROPORTIONING THE DROP IN 
THE VARIOUS PARTS OF THE SYSTEM.—THE CENTER OF 
DISTRIBUTION.—EXAMPLES OF THE EFFECTS OF DROP 
IN PARTS OF THE CIRCUIT.—EQUALIZING THE PRESSURE. 
—DYNAMOS FOR INCANDESCENT LIGHTING.—EFFECTS 
OF CHANGES IN THE FIELD OF DYNAMOS UPON THE 
LIGHTING.—A WIRING SYSTEM WITH FOUR CENTERS OF 
DISTRIBUTION.—THE LIFE OF A LAMP. 

Elements of a Wiring System.—The analysis of 
a wiring system discloses three fundamental ele¬ 
ments (Fig. 10), called mains, feeders and branches. 
These parts are subject to the same calculation for 
the discovery of the drop taking place in them as 
any simple circuit previously described. In laying 
out a waring system these elements must be care¬ 
fully considered and a great deal of discretion is 
necessary in making .allowance for the distribution 
of the total drop in each part. If, for instance, the 
total drop is 10 volts, and this is to be divided up 
between the elements above mentioned, the aver¬ 
age drop in mains, feeders, and branches would be 
3.333 volts. But there is no fixed rule for this con¬ 
clusion and the drop in the elements of a wiring 
system must be left largely to the judgment and 


64 


ELECTRIC-WIRING, DIAGRAMS 


experience of the contractor. To the contractor 
such questions arise in connection with this fact as: 
What is the cost of copper? What is the cost of 
labor? The labor question is by far the most im¬ 
portant one, because it would be easy to show by 
comparing the cost of materials included under the 
head of mains, feeders and branches as well as the 
moulding or tubing in which they would be laid 
with the cost of labor in installing them, that 
labor is of the first importance. One hundred 
dollars worth of materials may cost anywhere 
from $50 to $200 or more to install. It would be 
difficult indeed to attempt to give iron-clad rules 
for determining these relationships, but perhaps 
the best that can be done is to follow the common- 
sense rule of laying out the work so that the labor 
bill is low. Where it is possible to have a greater 
drop, and, consequently a lighter wire, and in 
some cases less labor in handling it, the choice 
becomes self-evident. When the cost of labor is 
equal in both cases, saving can only be attempted 
with the copper and the reverse, namely, when the 
cost of copper is equal in both cases saving must 
be attempted in the labor. Perhaps this idea can 
be best illustrated by a practical case (Fig. 11). 
Suppose 100 amperes are to be supplied to a set 
of feeders and branches, will it be necessary to use 
one or two pair of mains? If the wires are to be 
laid in moulding and run a distance of 100 feet, a 
calculation will show the size of wire required. 
According to the method a knowledge of the drop 


AND SWITCHBOARDS 


6 5 


to take place in the mains is necessary. If the en¬ 
tire drop is 3 per cent., an arbitrary choice of i per 
cent, can be considered, which at the usual voltage 
of no would mean i.i volts. The circular mils 
required are then ioo X 200 X n 1.1 —200,000, 
corresponding to a No. 4—o wire whose diameter is 
.4600 of an inch. If the wires are run straight 
ahead there is a possibility of using such a heavy 
wire but where there are bends, it is much more 
advisable to run two mains of 100,000 circular mils 
apiece or about No. o wire. This is true where 
moulding is used, although many might raise objec¬ 
tions to this conclusion on the grounds that it costs 
less to run a single line of 200,000 circular mils than 
two lines of 100,000 circular mils apiece. This mat¬ 
ter can only be decided by experience and even then 
a decision would rest largely upon the character of 
labor employed, which naturally involves questions 
of strength, skill and speed in the performance of 
duties. 

If a single line of 200,000 circular mils is in¬ 
stalled there is a saving in cost of material and 
labor, provided it takes less time to run the wires. 
A flexible cable might be employed and labor 
saved, but the wire costs more, so the point to be 
considered of cost of wire or material and cost of 
labor is in a practical sense a part of the triple 
question involved under the head of drop, material 
and labor. 

The arbitrary choice of 1 per cent, for the drop 
in the mains might have been made 2 per cent.; 

5 


66 


ELECTRIC-WIRING, DIAGRAMS 


in which case the size of wire being one-half or 
100,000 circular mils, the doubt disappears; but 
only i per cent, drop is left, and it is imperative to 
divide this up between the feeders and branches. 
If, putting the copper here, means more labor dis¬ 
tributed among a variety of wires, than putting it 
on the mains, then this is where less drop is most 
expensive. In the following sketch the elements 
of a wiring system are shown: 



Fig. io. —Elements of a Wiring System. 


In some cases the wires rising through the build¬ 
ing are called “ risers,” which would give four ele¬ 
ments instead of three, called mains, risers, feeders 
and branches. If the number of amperes are not 
too great the above system is satisfactory as in the 

















AND SWITCHBOARDS 


67 


case of a small factory. Where it is necessary to 
conduct a heavy current ,to each floor of a build¬ 
ing the design is changed in this respect; the num¬ 
ber of risers are increased. It is likely in such a 
case, the number of feeders are also increased, 



and in all probability the number of branches. 
But the difference is only in degree, that is to say, 
the new design would merely be a repetition of 
the last sketch. A case like this would arise where 
about 100 amperes are to be used on each floor of 
a three-story building, as shown in the above illus¬ 
tration : 

The foregoing sketches become very elaborate 
when a large structure is to be wired and every 






























68 


ELECTRIC-WIRING, DIAGRAMS 


circuit is shown in the drawing. In many cases 
where the total drop is very small, for instance, 2 
per cent., it is very difficult to divide the drop up 
between the various parts of the system in a 
scientific manner. The fact of greatest importance 
is this: that if a certain drop takes place in a build¬ 
ing it is due to a certain resistance and a certain 
current. Although more copper may be used in 
one part than another, it is evident that the sum 
total of copper will remain the same although its 
disposition will change. It is a good policy to make 
an allowance for overload in the mains and risers, 
in which case the drop will be less in the mains 
than any other part of the circuit in proportion to 
the rest. If for instance 2 per cent, is to be lost in 
drop and only of 1 per cent, in the mains, this 
would leave i-J per cent, for the rest of the circuit. 
Calculation will show how the sizes of wires would 
vary under these circumstances. The circular mils 
of the mains, risers, feeders and branches, on the 
basis of one estimate, can be compared with the 
circular mils estimated on a different basis, that 
is, a different arrangement of the percentages of 
drop equal to the total allowed. The following 
case is of interest in illustrating this idea: 

Example.—What sizes of wife are required to 
equip a building for electric lighting at no volts 
pressure, with a 3 per cent, drop, consisting of two 

floors (Fig. 12) taking 50 amperes apiece; the 

■ 

length of mains 50 feet, length of feeders 50 feet, 
and length of branches 25 feet. 


. AND SWITCHBOARDS 


69 


100 AMPERES 


FEEDER 50 FT. 


FEEDER 50 FT. 


BRANCHES 25 FT., 
10 AMPERES 


04 


Fig. 12. —Wiring System for Two Floors. 


The total drop is 3.3 volts, which may be divided 
up between the three elements equally for trial 
figures and for purposes of comparison as follows: 

Mains 100 feet wire, mains 1.1 volts drop, mains 
100 amperes: 


C. M. = 


100 X 100 X 11 
1.1 


100,000. 


Feeders 100 feet wire, feeders 1.1 volts drop, 
feeders 50 amperes: 


C. M. 


100 X 50 X 11 
-= 50,000. 


Branches 50 feet wire, branches 1.1 volts drop, 
branches 10 amperes: 


















































70 


ELECTRIC-WIRING, DIAGRAMS 


C. M. = 


50 X io X II 
1.1 


5,000. 


Arranging this data in the form of a table will 
show more clearly the comparison referred to and 
will embrace all conditions of drop, high and low, 
for each element of the circuit: 


Per cent, drop 
in volts. 


.1 

.2 

•3 

•4 

•5 

.6 

•7 

.8 

•9 

1.0 


Mains 100 feet. 
Circular mils. 


1,100,000 

520,000 

366,667 

275,000 

220,000 

I & 3>334 

I 57> 1 43 

i 37 > 5 °° 

122,222 

110,000 


Feeders 100 feet. 
Circular mils. 


520,000 

260,000 

1 73 ?333 
130,000 

104,000 

86,667 

74,285 

65,000 

57.777 

52,000 


Branches 
50 feet. 
Circular mils. 


55 ,°°° 

27,500 

* 8.333 

* 3 . 75 ° 

11,000 

9,166 

7-857 

6,875 

6,hi 

5.5oo 


If possible a table of this character should be 
drawn up for the various important parts of a wir¬ 
ing system as it will enable an accurate idea to 
be gained of the size and cost of installation as the 
percentage of drop in each element is modified. 

In the previous example the drop is equally 
divided between the elements constituting the cir¬ 
cuit. If this is not the case the results mav be 
tabulated for convenience and comparison as be¬ 
fore. As will be observed the total drop according 













AND SWITCHBOARDS 


7 1 


to the figures is the total allowed, namely, 3.3 volts. 
All the data is obtained from the last table: 


Comparative Table. 



Drop. 

Circular 

mils. 

Size 

wire. 

Mains. 

•5 

2 20,000 

4 — 0 

Feeders. 

1.0 

52,000 

3 

Branches. 

1.8 

3>°55 

U 

Mains. 

1.0 

110,000 

0 

Feeders . 

•5 

104,000 

0 

Branches. 

1.8 

3 >° 5 S 

U 

Mains. 

1.1 

100,000 

O 

Feeders. 

1.1 

50,000 

3 

Branches. 

1.1 

5, 000 

13 


A choice of wires is presented with which the 
wiring can be successfully accomplished. The first 
results in the table cannot be used because they 
call for the use of a 4—o wire. The second set of 
results are fairly uniform with the exception of the 
No. 15 wire, which is too small and forbidden by 
the Fire Underwriters. The last set of results are 
more satisfactory yet capable of further rearrange¬ 
ment to get the correct result. If it is possible to 
obtain a fair degree of uniformity in the sizes of 
wire a great advantage is gained as moulding or 
tubing can be bought to correspond and the work 
is, in a sense, simplified. 





















7 2 


ELECTRIC-WIRING, DIAGRAMS 


Center of Distribution. —In laying out a wiring 
system, one of the most important features is the 
selection of the center, or centers, of distribution. 
A wiring system is in many respects like a nervous 
system in its branches and ramifications, but the 
most interesting fact is the similarity between the 
ganglions in the nervous system and the centers 
of distribution in the wiring system. From these 
points, not only does the current become distrib¬ 
uted, but the pressure is delivered as nearly uni¬ 
form as possible to the various lamps or outlets 
at which it is utilized. An examination of the 
wiring of a large building discloses the fact that 
at one or more points on the floor, panel boards 
are in use, from which many lines run to lamps, 
or groups of lamps on the same floor. In smaller 
buildings the distribution may be different. One 
panel board may suffice for more than one floor, 
or, in other words, the centers of distribution are 
fewer, because the demand for current at given 
points is less. 

Example.—A single case may serve to illustrate 
the advantage gained by choosing a center or 
centers of distribution so far as the question of 
drop is concerned. Suppose a line 1,000 feet long 
consisting of No. io wire is supplied with current 
at no volts pressure and io lamps are to be lit at 
each end of the line; which is the best way of feed¬ 
ing current to the line so as to keep the drop at a 
minimum ? If the current is supplied from one end, 
the drop would be C X R = current of 20 lamps X 


AND SWITCHBOARDS 


73 


resistance of 2,000 feet of No. 10 wire = 10X2- 
20 volts. According to these figures the lamps 
nearest to the point at which the current enters 
would receive no volts minus 10 volts or 100 volts, 
and the lamps at the distant end 1,000 feet away 
would receive 10 volts less or only 90 volts. This 
would mean a heavy reduction in candle power 
and the failure of the plan as a successful wiring 
system. On the other hand, supposing the current 
is fed into the middle of the line, making this the 
center of distribution instead of the end, the con¬ 
ditions would then be different and the drop greatly 
reduced. Under these circumstances the current 
travels from the middle of the circuit 500 feet to 
each end of the line. The drop for each group of 
10 lamps at either end of the line is then equal to: 
Current of 10 lamps X resistance of 1,000 feet of No. 
10 wire = 5X1=5 volts drop. This means a great 
reduction in the drop for the lamps, uniformity of 
pressure for the lamps, and a much more efficient 
use of the copper employed in the line. If, instead 
of feeding into the middle of this 1,000 foot circuit, 
two lines or feeders are run 250 feet away from the 
ends, the drop for each group of lamps becomes: 
Current of 10 lamps X resistance of 500 feet of wire 
— 5 amperes X i ohm = 2.5 volts drop. 

The above figures are instructive in showing how 
the point or points from which the current is dis¬ 
tributed will influence the light or drop of the 
lamps. The following table indicates the effect of 
these changes: 


74 


ELECTRIC-WIRING, DIAGRAMS 


Ohms. 


Length of 
No. io wire. 
Feet. 

Am¬ 

peres. 

Drop 

in 

volts. 

2 

Feeding at one end. 

2,000 

IO 

20 

I 

Feeding at middle. 

1,000 

5 

5 

i 

Feeding at ^ from end.... 

666 

5 

3-333 

h 

Feeding at \ from end .... 

5 °° 

5 

2.500 


This idea is of the utmost value in street rail¬ 
way work, which in many respects possesses all 
the qualifications of a wiring system. The trolley 
wire is one leg of the circuit and the tracks the 
other, and between the positive and negative wires 
thus indicated, instead of lamps, as in the system 
of incandescent light wiring, trolley cars are run¬ 
ning. The current these cars take is the cause of 
a heavy drop on the line, which is to a large extent 
reduced by connecting into the line at definite 
points, feeders which supply both current and 
pressure where it is most necessary. By this 
means, a comparatively uniform pressure is pre¬ 
served throughout the line under all conditions of 
load. 

Equalizing the Pressure.—The choice of centers 
of distribution is for the purpose, as previously ex¬ 
plained, of equalizing the pressure. In house wir¬ 
ing, apartment houses and hotels particularly, dif¬ 
ferences in the illuminating power of lamps is 
prohibitive. It is necessary to use many centers 
of distribution to accomplish this object. In the 

















AND SWITCHBOARDS 


75 


following sketches (Figs. 13, 14 and 15) may be 
Been the development of this idea, as illustrated by 



CENTER OF DISTRIBUTION 


0 


;.o, 


1 




) 

<A 4 




Fig. 13.—One Center of 
Distribution. 



Fig. 14.—Two Centers 
of Distribution. 

















































76 ELECTRIC-WIRING, DIAGRAMS 


the case of one, two, three and more centers- of 
distribution. 














































































AND SWITCHBOARDS 


77 

Sub-centers of Distribution.—The main centers 
of distribution are of first importance in laying 
out the wiring system, but then come the second 
or sub-centers of distribution (Fig. 17), which are 
the means of transmitting the power to the lamps, 
etc., at approximately the pressure of the main 
centers of distribution. The same phraseology 
might be aptly applied with reference to mains, 
feeders, branches, etc., calling those which perform 
the same function in a secondary sense, sub-mains, 
sub-feeders, sub-branches, etc. The problem of dis¬ 
tributing the drop in the various elements of such 
a system in a practical, economical and scientific 
manner becomes a more difficult task as the various 
complexities of the system increase. The principle 
must be rigidly adhered to of calculating the drop 
for every line and part of the circuit, so that the 
total drop does not exceed the amount allowed for 
in the specifications. As a general rule the mis¬ 
take is made of not estimating the total drop from 
the source of supply through the circuit to the 
lamps it ends in as shown by the following simple 
sketch (Fig. 16) illustrating this important point 
in the calculation of wiring: 


78 ELECTRIC-WIRING, DIAGRAMS 



Fig. i 6.—Wiring Diagram Showing the Drop Limited 

to Two Volts. 

The drop from the source of supply to any group 
of lamps does not exceed 2 volts, as shown by trac¬ 
ing the circuit from the switch to the center of dis¬ 
tribution. 

From the switch through E to C = 2 volts. 

From the switch through F to A = 2 volts. 

From the switch through F to B = 2 volts. 

From the switch through F to G = 2 volts. 

From the switch through E to H = 2 volts. 

From the switch through E to D = 2 volts. 

The limit of 2 per cent, need not be observed so 
carefully in houses or buildings with their own 
generating plant. In such cases the pressure may 
drop 4 or 5 volts without any inconvenience on ac- 


















































AND SWITCHBOARDS 


79 


count of the character of the dynamo installed and 
the extra pressure generated to obviate this diffi¬ 
culty. 

Dynamos for Incandescent Lighting.—The class 
of dynamos employed for incandescent lighting are 
called shunt wound and compound wound. The 
shunt wound dynamo can produce a rise or fall in 
pressure by field regulation. In order to grasp this 
fact it is necessary to understand the fundamental 
principle relating to the generation of electromotive 
force, which may be popularly expressed in the fol¬ 
lowing words: Electromotive force is developed 
by a certain motion of conductors in a magnetic 
field or a certain motion of lines of force through 
a conductor. In other words, electromotive force 
is developed in a dynamo by motion, magnetism 
and conductors. A very simple formula expresses 
the relationship between these elements, based upon 
the manner in which a volt is generated. 

A volt is generated by the cutting of ioo million 
lines of force in one second. The formula is con¬ 
structed with the idea of giving the correct answer 
with any number of conductors, with any degree 
of motion and with any number of lines of force. 

Formula for calculating the emf. of a dynamo: 
The electromotive force is equal to the revolutions 
of the armature per second X the number of con¬ 
ductors on the armature X the number of lines of 
force passing through the armature, or 

speed per second X lines of force X conductors 

E. M. F. = —---rrp- 

ioo million. 




8o 


ELECTRIC-WIRING, DIAGRAMS 


It is expressed in symbols in the following form: 
E = N XcXiiv 100,000,000 where N = lines of 
force, c = conductors and n — speed per second in 
revolutions. 


CENTER CF DISTRIBUTION 



The entire purpose of this analysis is to show 
what a shunt machine is, and how it regulates its 
pressure, so that its relative importance to the 
wiring of a building and the lighting may be better 


















































































































































AND SWITCHBOARDS 


81 


understood, lhe emf. may be increased o 1 * dimin¬ 
ished by increasing or diminishing the conductors 
on the armature, the strength of field or the revo¬ 
lutions per second. As a general rule, the lines of 
force are increased or diminished to produce cor¬ 
responding changes in the emf. This is accom¬ 
plished by using a device called a resistance box 
connected in circuit with the winding of the mag¬ 
nets. If the handle of this box is turned one way 
or the other, the current is controlled, increased 
or diminished, and thus affects the power of the 
magnets, strengthening them or weakening them 
accordingly. If the dynamo must develop more 
pressure, the magnets are made to develop more 
magnetism by increasing the current passing 
through them, or vice versa. 

The meaning of this formula is best understood 
by developing a table showing with what combina¬ 
tions of magnetism, speed and conductors no volts 
can be generated in a dynamo: 


Revolutions 
per second. 

Conductors. 

Lines of force. 

Volts. 

IOO 

IIO 

1,000,000 

no 

50 

no 

2,000,000 

no 

50 

55 

4,000,000 

no 

2 5 

55 

8,000,000 

no 

12.5 

55 

16,000,000 

no 

2 5 

2 7-5 

16,000,000 

no 

10 

55 

20,000,000 * 

no 


6 















82 ELECTRIC-WIRING, DIAGRAMS 

Taking the above figures as a basis for estimat¬ 
ing, the emf. could be held constant while an in- 
finite variety of combinations would be possible in 
producing the same result. The lines of force are 
shown to vary from 1,000,000 to 20,000,000, with 
corresponding changes in the speed and conductors, 
thus passing from the class of machines called high 
speed to another class called slow speed generators. 
If the first line of figures is examined, the speed 
is indicated as 6,000 revolutions per minute and no 
conductors; to produce 1 volt additional at the same 
speed additional lines of force equal to 1,000,000 -r- 
110 or 9.091 are required. In other words, any 
change of pressure taking place in a dynamo, if not 
produced by a change in the speed or conductors 
is conveniently produced by a variation in the 
number of lines of force supplied to the armature. 

In the following table the changes in magnetic 
field required to produce a change of five volts in 
the pressure are shown with the speed and con¬ 
ductors constant: 


Table Showing Changes in Volts Through Changes in Field. 


Extra 

volts. 

Revolutions 
per minute. 

Conduc¬ 

tors. 

Field strength. 

Volts. 

O 

6,000 

no 

1,000,000 

no 

I 

6,000 

no 

1,009,091 

in 

2 

6,000 

no 

1,018,182 

112 

3 

6,000 

no 

1,027,273 

IX 3 

4 

6,000 

no 

1,036,364 

114 

5 

6,000 

no 

1 , 045,455 

“5 


















AND SWITCHBOARDS 


83- 


The resistance box connected to the field coils, 
as above mentioned, will therefore be the means of 
increasing the dynamos emf., but not necessarily 
the pressure it sends out. If the armature of a 
dynamo is regarded as part of a wiring system it is 
quite evident that, like any other conductor, an 
increase of current will mean an increase of drop. 
This being the case, the dynamo loses its own 
pressure as it is called upon for more and more 
current, so that if its original pressure was no 
volts, with only one lamp in circuit its pressure 
would be considerably lower at one-quarter, one- 
half and full load. The drop in the armature is 
not the only influence at work tending to lower the 
pressure of the dynamo. As the armature carries 
more current it becomes a stronger and stronger 
electro-magnet whose action upon the field in which 
it spins around is destructive. It reduces it sys¬ 
tematically and so effectively, that if external means, 
were not employed to compensate for this phenom¬ 
enon, electric lighting would become a difficult, if 
not an impossible task on a commercial scale. In 
shunt wound dynamos the regulation of pressure 
is accomplished by varying the field in the manner 
described and this obviates the evil effects of drop 
in the armature due to its resistance and the cur¬ 
rent it carries and the magnetic armature reaction 
which also takes place. But to regulate in this 
manner it is necessary to be in constant attendance 
upon the dynamo, unless some assurance is made 
that the changes in load will not take place rapidly. 





8 4 


ELECTRIC-WIRING, DIAGRAMS 


or unless the dynamo is of immense proportions 
and its armature, therefore, of such low resistance, 
that an increase of hundreds of amperes must oc¬ 
cur before any severe drop is felt. Regulation of 
pressure can be carried out practically and auto¬ 
matically by means of automatic dynamos called 
compound wound dynamos. These machines are so 
constructed, particularly their winding, that when 
the two losses, of drop and armature reaction take 
place, the dynamo automatically increases its own 
strength of field without the aid of any resistance 
box. A treatise on wiring is hardly the place to 
go into the technical features of dynamo construc¬ 
tion, except so far as they relate to the main point, 
the wiring problem; but it is evident that the wir¬ 
ing problem is to a large extent the problem of 
electric lighting, and this in itself calls for a thor¬ 
ough understanding of the differences in purpose 
of construction and operation of the generators 
employed. In the compound wound dynamos, to 
briefly conclude this explanation, the regulation is 
automatically accomplished by sending the main 
current around the field coils so that as this current 
increases or diminishes the strength of the mag¬ 
nets it circulates around, will also increase or 
diminish, and consequently the dynamos will pro¬ 
duce more volts only when the armature produces 
more current. 

It is of the utmost importance to remember that 
the shunt wound and compound wound dynamos 
are used for central station, street railway and pri- 


AND SWITCHBOARDS 


85. 

vate plants all over the United States for the 
generation of direct current. Many changes have 
taken place, so that the above statement does not 
hold true for all cases, or for the most modern 
plants. It does hold true, however, for such plants 
as are installed in public buildings, hotels, apart¬ 
ment houses, etc. The large station of the Edison 
Company at Pearl and Elm streets, New York, has 
several big generators, shunt wound, with resist¬ 
ance boxes in use for regulation in operation there. 

The wiring of buildings calls for a consideration 
of the above facts so that provision can be made 
in the distribution of the drop for the higher and 
lower pressure in the upper and lower parts of it. 
For instance, if a no volt generator is installed, of 
the automatic type, and it is over compounded, 
this means that it may produce 115 volts at one- 
quarter or one-half load, and then fall slightly as 
the load increases to 112 volts or a trifle more or 
less. In this case, considerable drop can be pro¬ 
vided for in the wiring of the lower half of the 
building. Where provision is ordinarily made for 
a drop limited to two volts, at least twice that drop 
can now be experienced with a corresponding sav¬ 
ing in copper in wiring the lower part of the 
structure. 

The resistances of the various mains, feeders and 
branches must be carefully calculated in conse¬ 
quence of this in order that the drop takes place, 
otherwise the lamps will deteriorate rapidly through 
excess pressure. Incandescent lamps are built to. 


'86 ELECTRIC-WIRING, DIAGRAMS 

give a certain candle power with a certain terminal 
pressure applied. If this pressure is too great the 
current increases to such a point that the life of 
the lamp is endangered by the overheating of the 
filament. The filament loses its resistance as it is 
heated. A 16 cp. no volt lamp cold has a resist¬ 
ance of about 450 ohms; when it is incandescent 
its resistance is about 225 ohms. As the filament 
is heated more and more its resistance becomes 
greatly reduced and five or ten more volts than 
the lamp is supposed to take greatly increases the 
current, the temperature and the light, and cuts 
down the period of usefulness. About 600 or 700 
hours, represents the effective light-giving period. 
It may, of course, be made to last much longer by 
keeping the pressure down below its proper value, 
but while the life of the lamp is increased the cost 
■of the light produced in this manner is very heavy 
as compared with the cost at the correct pressure. 
A few figures will illustrate this point clearly. If 
it costs $5,000 a year to produce 50,000 cp. in a 
building, including wages, depreciation of machin¬ 
ery, coal, etc., and the engineer tries to save the 
lamps by running the pressure low, he probably 
■cuts down the light 25 per cent, although full candle 
power is paid for. He saves an annual expense for 
new lamps of about $600, but throws away, so to 
:speak, $1,250 worth of light. Lighting under these 
■circumstances is a failure, giving no satisfaction 
for the money invested and represents the worst 
phase of false economy. 


AND SWITCHBOARDS 


87 


CHAPTER IV 

MEASUREMENT OF RESISTANCE.—PRINCIPLE OF THE WHEAT¬ 
STONE BRIDGE.—BALANCING THE RESISTANCE OF FOUR 
LAMPS.—MEASURING A LAMP HOT AND COLD.—MEASUR¬ 
ING INSULATION RESISTANCE.—THE INSULATION RE¬ 
SISTANCE OF BUILDINGS WIRED FOR ELECTRIC LIGHT¬ 
ING.—THE THREE WIRE SYSTEM COMPARED WITH THE; 
TWO WIRE.—CALCULATING THE THREE WIRE SYSTEM 
OF WIRING.—CIRCUITS OF A THREE WIRE SYSTEM 
WITH TWO CENTERS OF DISTRIBUTION.—CALCULATION 
OF POUNDS OF COPPER FOR MAINS OR FEEDERS. 

The laying out of circuits in many respects com¬ 
prises all that may be said about electric wiring, 
with the exception of a recognition of those prin¬ 
ciples which include a practical knowledge of the 
measurement of resistance. The measurement of 
.resistance is not limited to the measurement of the 
metallic resistance, but includes the insulation re¬ 
sistance as well. To measure any resistance calls, 
for a knowledge of the fundamental principle in¬ 
volved in the theory and operation of the Wheat¬ 
stone Bridge. 

The Wheatstone Bridge. — The Wheatstone 
Bridge is employed for the measurement of resist¬ 
ance and consists of a kite shaped arrangement of 
resistances in which each arm of the kite or bridge 


88 


ELECTRIC-WIRING, DIAGRAMS 


is a different resistance. In order to grasp the true 
significance of this device, a brief review of the 
situation with regard to resistances in multiple 
must be considered. According to Kirchoff’s law, 
the total resistance of any number of resistances 
in multiple can be readily calculated. Not only is 
the resistance estimated, but the current in each 
branch, and consequently the drop, is readily cal¬ 
culated. 

In the following sketches (Figs. 18, 19 and 20) 
the resistance and current are given; consequently 



Fig. 18.—Current in Each Branch. 



+ 


Fig. 19.—Resistance of Each Branch. 













AND SWITCHBOARDS 


89 

the drop in each branch is 12 volts respectively; 
that is to say, the application of 12 volts to a re¬ 
sistance of 2, 4 and 6 ohms, would mean a current 
of 6, 3 and 2 amperes and a drop in each circuit of 
12 volts. Such being 1 the case, the investigation 
of the conditions that exist in a circuit composed 
of resistances forming loops in multiple is similar 
in many respects to the conditions that exist in a 
Wheatstone Bridge. 



Fig. 20.—Drop in Each Branch. 


In a Wheatstone Bridge there are two resistances 
in multiple connected across by a galvanometer 
or some instrument of equivalent delicacy which 
indicates the existence of certain conditions. These 
conditions can only exist when the resistances bear 
a certain numerical relationship to each other. The 
relationship is simple and instructive and can be 
expressed by the conventional formula A: B as 
C: D, when A, B, C and D represent the four re¬ 
sistances obtained by connecting across the loop 
by a galvanometer as shown in Fig. 21. 







90 


ELECTRIC-WIRING, DIAGRAMS 


The real meaning of this remarkable relationship 
is, that when the ratio of A to B is the same as 
the ratio of C to D no current passes through the 



Fig. 21.—Wheatstone Bridge Obtained by Connecting Across with 

Galvanometer. 

galvanometer circuit and the bridge is said to be 
balanced. The explanation of the effect of this in¬ 
teresting condition is to be found in a careful ex¬ 
amination of the various drops occurring in the 
different parts of the circuit designated at A, B, C 
and D. If values are given to the resistances (Fig. 
22 ) comprising the respective parts of the Wheat¬ 
stone Bridge as shown, the following conditions, 
exist: 


Arm A drop 50 ohms X \ ampere = 25 volts. 
Arm B drop 100ohms X ^ampere = 25 volts. 
Arm C drop 150 ohms X ^ ampere =75 volts. 
Arm D drop 300 ohms X i ampere =75 volts. 








AND SWITCHBOARDS 


9i 


In other words, an examination of the theory 
and practice of the Wheatstone Bridge is merely 
an examination of the principles underlying the 
theory and practice of electric wiring. In the illus¬ 
tration it is shown that the points to which the 
galvanometer is connected are points at which the 
drop is equal and it follows that these are the only 
points in the circuit at which the galvanometer will 


1/2 AMPERE 



Fig. 22. —Calculating the Drop in a Bridge. 


remain at rest. It is therefore only necessary to 
provide a current and resistance at those points 
at which the galvanometer is connected whose 
product is equal at each end and the measurement 
of resistance becomes a practical possibility. 

In the practical application of the Wheatstone 
Bridge for the measurement of resistance the three 
arms as they are called, A, B and C, are utilized as 








92 


ELECTRIC-WIRING, DIAGRAMS 


follows: A and B are adjusted to a fixed ratio such 
as i: 2, i : io or io: 1,000, etc. C is then manipu¬ 
lated until a balance is struck, that is, until the gal¬ 
vanometer or indicating instrument is at rest. The 
conditions that then exist are that the arms express 
the ratio of A:B as C: D. In such a case as this 
D is the resistance to be found and it can only be 
found by balancing the bridge. To balance the 
bridge the unknown resistance is inserted in that 
part representing the D arm, and when the correct 
ratio is established the process is completed. The 
resistance of fields, armatures and other circuits is 
readily measured by means of the “ Bridge ” with 
an accuracy that is without its parallel in other 
allied sciences. 

One of the most instructing of experiments is 
that of constructing a Wheatstone Bridge of incan¬ 
descent lamps (Fig. 23) and noting the fact that 



Fig. 23.—Bridge of Incandescent Lamps, Middle Lamp Will Not 

Burn. 













AND SWITCHBOARDS 


93 


when the lamps in the four arms are burning the 
middle lamp will not burn. 

The entire situation can therefore be summed 
up in a word, that the drop must be equal in the A 
and B arms and the indicator or galvanometer will 
be at rest, and in order to secure this condition of 
affairs the resistances of the different arms must 
express the ratio of A: B as C: D. 

Examples.—If the A arm is io ohms, the B arm 
ioo ohms, and the C arm 99.9 ohms, what is the 
D arm ? According to the ratio D = B X C -f- A = 
100 X 99-9 -7- 10 = 999 ohms. Or the problem may 
be given in this form: The resistance of a tele¬ 
graph line is to be measured ; the A and B arms 
are set at the ratio of 10 to 1,000, the telegraph 
line consists of two loops of equal length and resist¬ 
ance, if the C arm causes a balance when it is 5 
ohms, what is the resistance of each loop of the 
telegraph line? Applying the formula D = 1.000 X 
5 -r- 10 = 500 ohms; but D = the resistance of two 
loops in multiple, therefore each loop is equal to 
1,000 ohms. 

Another example may be found in measuring the 
resistance of an incandescent lamp hot and cold. 
If the A and B arms represent the ratio of 10 to 
1,000, and the C arm reads 4.5 ohms, what is the 
resistance of a lamp in the D arm ? The lamp 
would have a resistance of 450 ohms cold but its 
resistance hot would be much less because when 
at incandescence it takes half an ampere and the 
resistance would be therefore no = 220 ohms. 


94 


ELECTRIC-WIRING, DIAGRAMS 


Almost any resistance high or low can be measured 
by the Wheatstone Bridge provided the galvanom¬ 
eter is delicate enough. The range of application 
reaches from .001 of an ohm to one million ohms 
with great accuracy, or a ratio of about 1 to one 
billion. 

Measuring Insulation Resistance.—The measure¬ 
ment of insulation resistance is one of the most im¬ 
portant features of electric wiring because of the 
requirements of the Board of Fire Underwriters, 
who represent the insurance companies, and the re¬ 
quirements, self-imposed, by the contractor’s con¬ 
science. 

Strange as it may seem to the uninitiated even 
the rubber or gutta percha covering of wires pos¬ 
sess a certain degree of conductivity. Where wire 
is used in large quantities this conductivity makes 
itself felt to such an extent that the resistance be¬ 
tween the copper wire and its covering is greatly 
reduced in proportion to the amount of wire used 
and the quality of the insulation employed. It is 
through this fact that the question of insulation 
resistance has arisen and requirements have been 
imposed limiting the amount of current and the 
insulation resistance in strict proportion to each 
other. In order to clearly convey an adequate idea 
of the meaning of insulation resistance as com¬ 
pared with metallic resistance a few illustrations 
will be necessary. 

Suppose 1,000 feet of No. 10 B. & S. wire are 
considered with a rubber covering of the regular 


AND SWITCHBOARDS 


95 


character employed for insulated wire; the metallic 
resistance is only i ohm, but the insulation resist¬ 
ance may be anywhere from 100,000 to 1,000,000 
ohms. Supposing the insulation resistance is taken 
at 100,000 ohms, then the question arises, what is 
the insulation resistance per foot, per yard and per 
hundred feet? This question can best be answered 
by means of an illustration (Fig. 24) conveying 
the correct idea. 




1000 FT. INSULATED WIRE 


INSULATION RESISTANCE 100,000 OHMS PER 1000 FT. 


5 = 


500 FT. .INSULATED WIRE 




INSULATION RESISTANCE 200,000 OHMS 


500 FT. 


250 FT. 


INSULATED WIRE 


v- 




INSULATION RESISTANCE 400,000 OHMS 


250 FT. 


i 1?5 FT. 0, 
T)|NS.WIREJ > 


INSULATION RESISTANCE 800,000 OHMS 


125 FT. 


Fig. 24.—Insulation Resistance of Various Lengths of Wire. 


The insulation resistance as shown by the illus¬ 
tration follows just the reverse rule of the metallic 
resistance. The insulation resistance increases the 
shorter the wire. If the data suggested by the 
above sketches is tabulated the following figures 


occur: 










96 ELECTRIC-WIRING, DIAGRAMS 


Length of wire. 

Feet. 

Resistance of insulation. 

Ohms. 

1,000 

100,000 

5 00 

200,000 

250 

400,000 

125 

800,000 

IOO 

1,000,000 

50 

2,000,000 

IO 

10,000,000 

I 

100,000,000 


The lesson taught by the above results is this, 
that the insulation resistance of each foot of wire 
must be very high in order to give a high general 
insulation resistance. The resistance of the wire 
may reach the same figure as the insulation resist¬ 
ance if enough of it be used as shown by the follow¬ 
ing figures: 


No. 10 B. & S. 
Feet. 

Resistance. 

Ohms. 

Insulation resistance. 
Ohms. 

1,000 

I 

100,000 

2,000 

2 

50,000 

10,000 

IO 

10,000 

100,000 

IOO 

1,000 

300,000 

300 

333 

1,000,000 

1,000 

IOO 


The insulation resistance falls below the metallic 
resistance according to the above figures when the 














AND SWITCHBOARDS 


97 


length of wire becomes greater than 300,000 feet 
of wire. This amount of wire seems enormous, but 
when the amount of wire installed in a World's 
Fair is considered and the wire installed in a 20- 
story skyscraper in New York City the drop in in¬ 
sulation resistance is a foregone conclusion. The 
question of insulation resistance is not merely that 
of the wires installed in a building, but also relates 
to power lines. The necessity for the use of relays 
in telegraphic service is largely due to the fact that 

the current leaks awav in transit from one station 

* 

to the other. As an example-of this, supposing a 
telegraphic line 1,000 miles in length is considered. 
Wherever it is supported there is a glass insulator 
of at least 5,000,000 ohms (5 megohms) resistance. 
Every 200 feet (Fig. 25) another pole is erected, 


200 FT. 200 FT. 200 FT. 200 FT. 




• 13 

P *3 


h id 

k 1 4 

p 1 









1 



-4- 




j 




[station 



LEAKAGE 



[station 


Fig. 25. —Conditions Existing in a Long Distance Line. 


making about 25 insulators to the mile. Over a 
distance of 1,000 miles 25,000 insulators are neces¬ 
sary. This means an insulation resistance of 5,000,- 
000 -7- 25,000 = 200 ohms over the line from end to 
end. This is under the best of conditions, when 
for instance the air is dry and the insulators clean, 
but in wet or stormy weather the conditions are 
different. The insulation resistance of not only 
7 



















g& ELECTRIC-WIRING, DIAGRAMS 

telegraph poles and lines but power lines as well 
drops considerably and a heavy leakage is apt to 
result. In the case of telegraph lines copper wires 
and high grade insulators may prove of some avail, 
jbut where serious leakage occurs with high tension 
power circuits a grave risk is incurred, beside 
which the mere question of the cost of power 
wasted loses its significance. 

Measurement of Insulation Resistance. —To meas¬ 
ure a resistance of millions of ohms or megohms 
calls for a delicate and high resistance galvan¬ 
ometer and a box of high resistance coils (Fig. 
26). As shown in the sketches, the first process 



Fig. 26.—Connections for First Reading. 

is to connect the coils and galvanometer in series. 
Supposing the coils are unplugged and represent 
200,000 ohms and the galvanometer gives a reading 
of 20 divisions. The next step is to substitute the 
insulation resistance for the box of coils. The coil 

‘ > * 1 / - *. 

of wire is taped at one end and then immersed in 
a boiler of water or any other convenient metal 
receptacle (Fig. 27). The free end is connected in 
circuit and the metal vessel likewise connected as 
shown. The second reading may now be taken, 









AND SWITCHBOARDS 


99 


it will be very low in all probability. If it is I 
division, then the resistance must be 20 X 200,000 
ohms = 4,000,000. 



Fig. 27. —Connections for Second Reading. 


The current which has actuated the galvanometer 

o 

has found its way through the insulation resist- 
ance of the wire and therefore the galvanometer 
indicates the respective quantities of current which 
flow when 200,000 ohms is in circuit in one case 
and the unknown insulation resistance in the other 
case. Interesting examples can be given in connec¬ 
tion with the wiring of buildings as follows: 

Example.—What is the insulation resistance of 
a building using 20,000 feet of wire, the insulation 
resistance per foot being 10 megohms? The an¬ 
swer is readily obtained by dividing 20,000 feet 
into 10,000,000 ohms giving the result 10,000,000 
20,000 = 500 ohms. In other words, the follow¬ 
ing fact appears: That as the wire increases in 
length its metallic resistance increases but its in¬ 
sulation resistance decreases. 

Kinds of Insulation.—The insulating material in 
vogue for the covering of copper wires may be 
roughly divided into four general classes. First, 








IOO 


ELECTRIC-WIRING, DIAGRAMS 


rubber; second, gutta-percha; third, composition, 
and fourth, cotton covering. The last, namely cot¬ 
ton, is in use for magnet and armature wire; the 
first is generally employed for electric light wire 
which is usually advertised as rubber covered wire. 
Cotton covering saturated with paraffin is used in 
enormous quantities for bell and annunciator work, 
but a great deal of wire covered with composi¬ 
tion is also employed for this purpose. Atlantic or 
submarine cables are generally protected by gutta¬ 
percha coverings from the action of water but, in 
the course of time, changes in the character of the 
insulation take place and the rubber, gutta-percha, 
and particularly the composition coverings break 
down and the insulation resistance rapidly dimin¬ 
ishes. The deterioration is not of serious conse¬ 
quence if the wires are well protected in mould¬ 
ing or conduit, but in old-fashioned buildings, 
wired ten or more years ago, the risk of fire due 
to the general deterioration not only of the insula¬ 
tion but the switches, sockets, etc., is very great. 
The requirements of the Board of Fire Under¬ 
writers can be had on application, and a review 
of the conditions imposed will show the necessity 
for the selection of the best switches, sockets, 
wire and conduit in the equipment of a building 
for electric lighting. The systematic tests for in¬ 
sulation resistance which should be carried on will 
be a good indication of the value of the materials 
employed. If the lines are free from grounds and 
similar defects and the insulation resistance keeps 


AND SWITCHBOARDS 


IOI 


falling it is a sign of the defective nature of the 
insulating covering of the wires. 

The Three-wire System. —The two-wire system 
has been developed into a method of wiring, 
through which a great saving in copper is made. 
The employment of this method, under the title 
of the “ three-wire system,” by the present light¬ 
ing company in New York City, and its installa¬ 
tion as the wiring of thousands of private and pub¬ 
lic buildings establishes it as an economical and 
practical means of distributing current for electric 
lighting. 

The idea involved is that of making a more effi¬ 
cient use of the copper than would be possible in 
the method of employing only two wires for elec¬ 
tric lighting, as previously described. To illustrate 
theoretically and practically the advantages of the 
three-wire system reference must be made to the 
general principle underlying power transmission 
and its relation to the pressure in volts at which 
it is transmitted. The principle is stated as fol¬ 
lows : 

Principle. —The weight of copper required for 
the transmission of a given amount of power is 
inversely proportional to the square of the pressure. 
By this is meant, that if ioo hp. is transmitted at 
ioo volts pressure, and a certain weight, say 2,000 
pounds of copper, is required, then at twice the 
pressure or 200 volts only one-quarter or 500^ 
pounds of copper would be necessary. The fol¬ 
lowing table is instructive in showing how ad- 


102 


ELECTRIC-WIRING, DIAGRAMS 


vantageous it is to use high pressures for the 
transmission of power in comparison with low 
pressures as far as the saving of copper is con¬ 
cerned. Taking the case of ioo kilowatts to be 
transmitted at ioo volts over a thousand foot run 
the following data appears: 


Volts. 

Circular 

mils. 

Kilo¬ 

watts. 

Length 
of wire. 
Feet. 

Weight 
of wire. 
Pounds. 

Drop. 

Volts. 

IOO 

440,000 

IOO 

2,000 

2,666 

5 

200 

110,000 

IOO 

2,000 

667 

10 

400 

27,50° 

IOO 

2,000 

167 

20 

800 

6,875 

IOO 

2,000 

42 

40 

1,000 

4,400 

IOO 

2,000 

27 

50 

2,000 

1,100 

IOO 

2,000 

7 

IOO 


The remarkable reduction in the size of wire re¬ 
quired for the transmission of ioo hp. at ioo volts 
and at 2,000 volts, namely, 440,000 circular mils 
and 1,100 circular mils, is an object lesson in 
finance to builders of power transmission lines. 
The requirements for insulation naturally increase, 
but the cost of erecting the wire becomes much 
less on account of its lightness. A heavy line re¬ 
quires strong supports and great expense is in¬ 
volved if storms affect -the stability of the line 
while in service. This is largely obviated where 
a light wire is run, that is to say, where a high 
pressure is employed. 
















AND SWITCHBOARDS 10 $ 

The three-wire system installed by the Edison 
Company in the streets of New York- consists of a 
network of copper embracing all of the downtown 
or business territory and following up the maiii 
thoroughfare, Broadway, with extensions to either 
side, thus covering an extensive area. If the three- 
wire system were not employed, that is, if the two- 
wire system were in its place at present, nearly 
three times as much copper would be in use to' 
transmit the same amount of power. If,- for in¬ 
stance, the above company has $1,000,000 worth 
of copper underground with the three-wire system,- 
with the two-wire system there would be almost 
$3,000,000 worth installed. The principle,’ there¬ 
fore, has immense economical and practical advan¬ 
tages over the two-wire and in the following ex¬ 
planation the facts relative to this saving will bd 
made clear: 

Suppose 100 lamps are to be lit on a ioo-foot ruri 
at no volts pressure, then the size of wire accord^ 



Fig. 28.—220 Volt Two-wire System Feeding 100 Lamps in Groups of 
Two in Series with 2 Per Cent. Drop. 

ing to the rule at a 2 per cent, drop would be 5,50c) 
circular mils or a No. 13 wire B. & S. gauge. If 
the voltage is doubled then 220 volts would call 
for every two lamps to be in series (Fig. 28) f 






io 4 ELECTRIC-WIRING, DIAGRAMS 

which would mean 50 sets of lamps of two in 
series, requiring only one-half the current of the 
other circuit of lamps. The first circuit called for 
50 amperes for 100-110 volt lamps on a two-wire 
circuit or 55,000 circular mils. The second circuit 
with every 2 lamps in series and 220 volts press¬ 
ure, calls for only 25 amperes. The drop in the 
second circuit is 2 per cent, or 4.4 volts while it is 
only 2.2 volts in the first circuit. In the second 
circuit, therefore, with 220 volts pressure, not only 
is one-half of the current required, which reduces 
the circular mils one-half but twice as many volts 
can be lost, which reduces the circular mils again 
to one-half. In other words, if a 220 volt pressure 
is used with the lamps arranged in groups of two 
in series, as shown, only onc-quartcr of the circular 
mils and therefore the weight of copper need be 
employed. 

But in the sketch shown, the number of lamps 
can be divided by 2; if one should burn out, the 
other connected to it would also go out, and this 
would make the system impracticable. Another 
reason why the system previously mentioned would 
be useless is where the number of lamps are un¬ 
equal, that is, not divisible by two. The use of 
the neutral wire shown in the sketch (Fig. 32) 
entitled “ The three-wire system balanced,” does 
away with both of these difficulties. In the sketch 
(Fig. 29) the three-wire system is shown un¬ 
balanced and the use to which the neutral wire 
is put in such a case. Its function is merely to 


AND SWITCHBOARDS 


io 5 

take up and transmit the current of the difference 
between the two sides of the circuit. If the neutral 


A B 


J-l 11 

) 0 

1" 


O O 

0 


0 

0 < 

< 

0 

T ° 

< 

0 

<> O 


() 

—O— 


Fig. 29. —The Three-wire System Unbalanced, Showing the Use of 
Neutral Wire with Respect to Three Lamps. 

wire were not employed, the amount of copper used 
at 220 volts, with groups of two lamps in series, 
would be only one-quarter, but with the neutral 
wire, for purposes of illustration, the same size as 
the two others, the amount of copper used becomes 
i + i + 4 — t of what would be required to light 

100 FT. 



Fig. 30.—Two-wire System. Size of Copper Wire. Lighting 100 
16 Candle Power Lamps, 2 Per Cent. Drop. 


100 FT. 

_ (1 = 117 OR 13750 C. M, =- No. 9 B. AND S. _ 1 * 

Fig. 31. —Three-wire System. Size of Copper Wire. Transmitting 
the Same Power, 2 Per Cent. Drop. 

the same number of lamps at no volts by the two- 
wire system. The exact difference in the size of 
copper is shown by the sketches (Figs. 30 and 31) 







































































































io6 ELECTRIC-WIRING, DIAGRAMS 


both as regards diameter in inches and circular mils 
in cross section. 

A simple calculation for obtaining the size of wire 
with a three-wire system with the same percentage 
of drop as a two-wire system is to employ the 
old formula with 4 in the denominator as follows: 
Circular mils = amperes X length of wire in feet 
X 11 -r volts drop in line X 4 , or, symbolically. 


C. M. = 


11 X feet X C 
4 X E 


As regards the neutral wire in the laying out of a 
street system, such as is employed in New York, 
it is not as thick as the two outer wires but con¬ 
siderably less. The reason for this may be found 
in the fact that the lighting company will not 
turn current on the premises unless the lights are 
well balanced, therefore the amount of current 
carried by the middle wire is very small and its 
cross section in consequence is much less than 
the two outer wires. If the balance is fairly even 
throughout the district supplied with current, the 
generators connected to the circuit (Fig. 32) will 
carry equal loads; should a great difference of bal¬ 
ance exist, however, the load would become very 
heavy on one machine to the exclusion of the other 
and its injury would result. If the balance is on 
the average fairly good, the saving of copper 
through the neutral wire being small is greater,, 
and instead of .375 of the copper being used, less 
will be required as compared with a two-wire sys- 



AND SWITCHBOARDS 


107 

tem. The same general ideas are carried out in 
the equipment of a building for a three-wire system 
as for a two-wire, with the addition that particular 


POSITIVE LEG 



Fig. 32. —The Three-wire System Balanced. 


care is taken to keep the circuits balanced. In the 
following illustration (Fig. 33) is shown the gen¬ 
eral scheme of a three-wire system, lamps equally 
balanced, and special motor lines of 220 volts 
apiece. The idea can be still further carried out 
for a more extensive and more complicated circuit. 
The neutral wire in a perfectly balanced system is 
hardly necessary except in such cases as a few 
lights more are kept burning on one side of the 
circuit than on the other. 

Combination of Two and Three-wire Circuits.— 
In many instances where private plants are in¬ 
stalled, the danger of a break-down has led the 
proprietor to make provision for such an emer¬ 
gency by having the wiring done so as to take cur¬ 
rent from the street if necessary, without risking 























io8 ELECTRIC-WIRING, DIAGRAMS 


the lamps in ordinary use. This is accomplished 
by equipping the building with the three-wire sys¬ 
tem but making the neutral wire of twice the cross 


220 VOLT MOTOR 































































































































AND SWITCHBOARDS 


109 


section of the two outer wires. By this means both 
a no-volt two-wire system and a 220-volt three- 
wire system are combined (Fig. 34) and the equip- 



Fig. 34.—Combination of Two and Three-wire System for Protection 
Against Break-down of Private no-Volt Two-wire System. 

ment will work admirably on either, if the circuits 
are balanced. There is a distinct saving of copper 
by this method of wiring over the two-wire system, 
because according to the figures previously given, 
three wires, if of equal size, represent .375 of the 
copper which would be required in a two-wire sys¬ 
tem of equal capacity. Each wire is therefore one- 
eighth, and if the middle wire is twice the circular 
mils of the other two the total will be + i + i = 
or .50. In other words, a building wired accord- 















































no 


ELECTRIC-WIRING, DIAGRAMS 


ing to the above requirements is still using only 
one-half the copper otherwise required by a two- 
wire system. 

In handling heavy wires it is frequently neces¬ 
sary to be able to calculate the weight of the wire, 
as for instance in considering the mains and feeders 
of a large installation. The formula for doing this 
is as follows: 


Pounds per foot of copper = circular mils 

-f- 62.5 X 5,280 = 


C. M. 

62.5 X 5,280’ 


By leaving out the 5,280 the weight of copper per 
mile is obtained and the formula becomes: Weight 
in pounds per mile = C. M. -f- 6.25. In power lines 
for motors or lighting, this calculation is very valu¬ 
able, as in the preparation of estimates many 
means are adopted to keep the weight of copper 
down. 

Example.—As an example of the above, suppose 
200 hp. is to be transmitted one mile at 500 volts 
and 5 per cent, drop, what is the size and weight 
of the wire? 

m, . \ 300X10,560X11 

I he circular mils = -= 1,393,920. 

2 5 


I 3Q3 Q20 

The weight per mile = - ^ — = 22,303 pounds for a 

* 5 

single wire or a total of 44,606 pounds per mile. 


The weight per foot = r T 393 > 9 2 o = g pounds, 

62.5 X 5,280 ^ 






AND SWITCHBOARDS 


in 


The above figures are indicative of the necessity 
of estimating drop as high as is consistent with 
good engineering or the weight of the copper be¬ 
comes excessive. 

The law promulgated by Lord Kelvin years ago 
reads as follows: The cost of copper must be such 
that the interest on the investment shall not exceed 
the cost of wasted power in the line. The meaning 
of this is that with $100,000 spent for copper in a 
transmission system only $6,000 worth of power 
should be wasted, because this represents the in¬ 
terest on the investment. 


112 


ELECTRIC-WIRING, DIAGRAMS 


CHAPTER V 

TYPES OF MOTORS.—CONNECTIONS OF MOTORS.—MEANING 

AND REASON FOR BACK ELECTROMOTIVE FORCE.- 

USE OF A STARTING BOX.—METHOD OF CONNECTING 
UP A SHUNT WOUND MOTOR.—HORSE POWERS OF 
MOTORS AND EFFICIENCIES.—EFFICIENCY OF MOTORS 
AND SIZE OF WIRES.—ADVANTAGE OF HIGH PRESS¬ 
URES.—THE ALTERNATING CURRENT FOR LIGHTING.— 

/ 

MEANING OF FREQUENCY OR CYCLES. 

The subject of wiring is closely related to power 
transmission both as regards the wiring and the 
motors operated from distant sources of power. 
It is within the scope of wiring treated as a science 
as well as an art to consider the motor and briefly 
outline its principles of operation and construction. 
Motors are generally divided up as far as continu¬ 
ous current circuits are concerned into three great 
classes as follows: 

The Series Wound. 

The Shunt Wound. 

The Differentially Wound. 

This classification relates to the winding of the 
magnets or fields, as they are commonly called. 
The manner in which the field is affected by the 
current flowing through its coils is indicated in the 
above tabulation and sketches (Figs. 35, 36 and 37). 


AND SWITCHBOARDS 


“3 



Fig. 35.—Connections of a Series Wound Motor. 



Fig. 36.—Connections of a Shunt Wound Moto\. 



The Principle of the Motor.—The motor and 
dynamo are reversible machines, the dynamo trans¬ 
forming mechanical energy into electricity, the 
8 



























11 4 ELECTRIC-WIRING, DIAGRAMS 

motor transforming electrical energy into mechan¬ 
ical force. Any well made dynamo will operate 
successfully as a motor, in fact there is in many 
cases only a difference in name between the two 
machines. A dynamo is a machine in which the 
movement of conductors through the magnetic 
.field (Fig. 38) means the development of electro- 



Fig. 38.—Conductor Cutting Lines of Force. 


motive force. As these conductors produce more 
current the source of mechanical energy is called 
upon to deliver more power until a balance is estab¬ 
lished. In a motor the same conditions exist in a 
-reverse manner; the demand for more current takes 
place automatically until sufficient enters to do the 
work required by the outside load, whereas in the 
dynamo the extra lamps or motors turned on rep¬ 
resent the demand for more current, and hence 
:more mechanical energy. In the motor the extra 
current automatically and instantaneously augments 
as extra strain is put upon the motor. In the motor 
as well as the dynamo conductors rotate in a mag¬ 
netic field. The consequence is that electromotive 
iorce is developed which in the case of the dynamo 









AND SWITCHBOARDS 


n 5 

is utilized for lighting, etc., but in the case of the 

motor this electromotive force is opposed to the 

* 

electromotive force sending a current through the 
armature and is therefore called the “ back emf.” 
The armature of a motor is simply an electro-mag¬ 
net which experiences a series of attractive pulls, 
when current enters its winding through the action 
of the commutator and the position of the brushes. 

The commutator and brushes constitute an auto¬ 
matic switch which sends the current into certain 
coils in certain positions on the armature. These 
coils magnetize the core of soft iron and a powerful 
tractive effort develops between the armature and 
the magnetic poles which embrace it. Summing 
the phenomena up, therefore, the action in a motor 
is simply the attraction between opposite magnetic 
poles which results in continuous rotation. As far 
as the mechanical results are concerned this is 
about all that need be said in a brief review of the 
situation, but the reactions occurring within a motor 
call for recognition in the scheme of wiring and 
reference must therefore be made to them. 

Effect of Back emf. upon Wiring.—The armature 
of a motor cannot instantaneously spin around at 
a high rate of speed, when current is turned on, 
therefore it cannot generate a back emf. in time to 
stem the flood of current which will pour through 
it. A heavy flow will take place because the re¬ 
sistance of the armature is too low to prevent it. 
It is necessary to interpose between the armature 
and the line a resistance (Fig. 39) sufficiently great 




n6 ELECTRIC-WIRING, DIAGRAMS 


to check any unusual flow of current. In the shunt 
and differentially wound motors this is imperative; 
in the series wound motor it is only necessary under 



Fig. 39.—Principle of the Connections of a Shunt Motor. 

■certain circumstances. The current is restrained 
until the armature has gained sufficient speed to 
generate the required back emf. to establish a bal¬ 
ance between the power entering the motor and 
the effort called for by the load. The resistance 
is then cut out and the motor regulates its own 
influx and efflux of current by the back emf. and 
this in its place is regulated by the load. In the 
following sketch (Fig. 40) a shunt motor is shown 
with the starting box interposed when the armature 
begins to rotate. The boxes are so constructed 
that the final movement of the handle cuts out all 
resistance and connects the motor to the mains. 

Points About Motors.—In the wiring of a shunt 
motor the fields must be on first and the pole pieces 
must be tested to discover this fact. Next, the cur¬ 
rent must pass into the motor through the resist¬ 
ance box and the armature will start slowly. The 
final throw of the handle of the starting box must 















AND SWITCHBOARDS n 7 

not cause any unusual development of speed. A 
series motor must never be started without a load 
on. If this rule is not observed the motor will ro- 



Fig. 40.—Practical Connections of a Shunt Motor. 


tate at an enormous rate of speed, each accession 
of speed developing a velocity which will only cease 
by the opening of the switch or the destruction of 
the motor. 

A differentially or compound wound motor repre¬ 
sents a combination of the two windings. The 
principle involved is this: that by weakening the 
field of a shunt motor the speed of the armature 
increases. In consequence, the current in the series 
coil of the motor tends to reduce the strength of 
field and increase its speed when the load tends to 
diminish it. 

Efficiency of Motors. —The efficiency of the motor 
























ii8 ELECTRIC-WIRING, DIAGRAMS 


is twofold, the electrical efficiency and the commer¬ 
cial efficiency. The electrical efficiency is the ratio 
between the back emf. and the impressed or ex¬ 
ternal emf. The commercial efficiency is the ratio 
between the power given out by the motor and the 
power it absorbs. Unless a motor has a high elec¬ 
trical efficiency it cannot have a high commercial 
efficiency. The back emf. and therefore the elec¬ 
trical efficiency can be calculated in the following 
manner: Multiply the resistance of the armature by 
the current and subtract the product from the im¬ 
pressed emf. to get the back emf. For instance, 
suppose a motor has an armature resistance of .01 
of an ohm and takes 50 amperes at no volts, what 
is the back emf.? According to the above principle 
50 X-Oi = .50 and subtracting .5 from no gives 

109.5 back emf. The electrical efficiency equals 

109.5 -riio or 99.5 per cent. If the power devel¬ 
oped in this case equals 5 lip. then the commercial 
efficiency equals 5 X 74^ -r- 5,500 = 3,730 -f- 5,500 = 

67.5 per cent. 

I11 motor wiring calculations the commercial effi¬ 
ciency is of the greatest consequence if given in 
connection with the emf. of the motor. The cir¬ 
cular mils required for a motor line can be calcu¬ 
lated if the horse power of the motor, its efficiency, 
the voltage, the length of the line and the drop are 
given. The formula for calculating the circular 
mils is as follows: 

£ _ HP. of motor X 746 X length of wire X 11 

volts of lines X drop X efficiency in $>. 






AND SWITCHBOARDS 


i igr 

Taking a practical case, what are the circular mils 
of a motor line with the following data: 

HP. of motor = io. 

Length of run = 200 feet. 

Volts of line = 220. 

Drop of line = 10 volts. 

Efficiency = 80 per cent. 

C. M. = 10 X 746 X 400 X n 4- 220 X 10 X .80 
= 18,650 or a No. 7 B. & S. To check the results, 
find the resistance of 400 feet of No. 7 wire and 
multiply by the current, which in this case is ap-~ 
proximately 50 amperes. 

Resistance 400 feet No. 7 = .2 ohm. .2 X 50 = io 5 
volts drop as indicated above. 

The efficiencies of motors vary very much, but 
the average efficiency of the general run of direct 
current motors can be summed up in the following 
figures: 


Horse power. 


1 

2 

3 

4 

5 

6 

7 

8 

9 

10 


Efficiency. 


70 per cent.- 
7 5 per cent.- 
80 per cent.- 
82 per cent.- 
85 per cent. 

87 per cent. 

88 per cent. 

89 per cent. 

90 per cent. 

91 per cent. 







120 


ELECTRIC-WIRING, DIAGRAMS 


A comparative table showing the relationship 
between the efficiency of a motor and the size of 
wire required will be instructive in showing how 
a low efficiency and high efficiency motor affect 
the contractor’s expense in wiring: 


Efficiency of motor. 

Circular mils. 

50 per cent. 

29,840 

55 per cent. 

2 7> I2 7 

60 per cent. 

24,866 

65 per cent. 

22,938 

70 per cent. 

2 i, 3 I 4 

75 per cent. 

19,893 

80 per cent. 

18,650 

85 per cent. 

* 7,553 

90 per cent. 

16,577 


The above table is built from the problem just 
given with a io hp. motor and 80 per cent, effi¬ 
ciency, only the efficiencies are varied to show the 
change in the size of wire required. This problem 
is of the utmost importance, particularly in power 
transmission, where the weight of copper when 
heavy horse powers are transmitted becomes enor¬ 
mous unless limited by high pressures and efficien¬ 
cies. The weight of copper can be likewise devel¬ 
oped with respect to the efficiency as shown in the 
following table, in which one mile of wire is con¬ 
sidered, a io hp. motor and 500 volts pressure: 







AND SWITCHBOARDS 


121 


Efficiency. 

Weight in pounds per mile. 

50 

1,109 

60 

924 

70 

792 

80 

693 

90 

616 


The tendency on all sides is to adopt high press- 
ure systems which represent a combination of direct 
and alternating current machinery. 

The Alternating Current. —In the lighting of in¬ 
candescent lamps alternating as well as direct cur¬ 
rent is employed. The alternating current differs 
from the direct current in so far as it consists of 
a series of systematic impulses or waves which 
rush back and forth in the circuit a certain number 
of times a second. The dynamo generating an 
alternating current becomes an alternator simply 
because it has no commutator, the armature wind¬ 
ing ending in two rings instead of being connected 
to copper strips insulated from each other. The 
direct current dynamo also generates an alternating 
current, but this current is modified in the sense 
that its impulses are all sent along in the same 
direction by means of the commutator and brushes. 
The original name for the commutator was recti' 
fier, because it rectified the impulses. There are 
various characteristics to alternating currents which 
must be known in the handling of them for com¬ 
mercial purposes. 








122 


ELECTRIC-WIRING, DIAGRAMS 


The frequency or number of periods per second 
is the term used to define the number of complete 
reversals (Fig. 41) of current per second. Each 



Fig. 41. —Rise, Fall and Reversal of Electromotive Force in an 

Alternator. 


complete reversal is due to the wire passing two 
poles—a north and a south pole. While passing 



Fig. 42. —Elements of an Alternator. 

before the north the current flows in one direction 
(Fig. 42), and when passing the other in the oppo- 






























































AND SWITCHBOARDS 


123 


site direction. The frequency or number of periods 
per second can therefore be calculated in the fol¬ 
lowing manner: 

Frequency. — The frequency = revolutions per 
second X one-half the number of poles. For in¬ 
stance, what is the frequency of an alternator with 
8 poles and a speed of 30 revolutions per second? 
Frequency = 30 X 4 = 120 reversals. The utiliza¬ 
tion of an alternating instead of a direct current is 
due to many advantages in transmission possessed 
by an alternating current system over a direct. 
This first manifests itself in a great saving in 
copper and power, secondly in cost of construction 
of both dynamos and line. In connection with 
wiring the question which arises is this, “ Is the 
line inductive or non-inductive? ” In other words, 
are coils in any way associated with the circuit so 
as to develop reactive electromotive forces or not. 
It is therefore necessary in preparing the plans of 
an alternating current lighting .and power system 
to be sure that the circuits are free from disturbing 
inductive influences. 


124 


ELECTRIC-WIRING, DIAGRAMS 


CHAPTER VI 

REASONS FOR EMPLOYING CONDUIT.—THE USE OF CLEATS.— 
THE USE OF MOULDING.—IRON ARMORED CONDUIT.— 
ENAMELED IRON CONDUIT.—BRASS ARMORED CONDUIT. 
—ASPHALTIC PAPER TUBE OR PLAIN CONDUIT.—FLEX¬ 
IBLE WOVEN CONDUIT.—FLEXIBLE METALLIC CONDUIT. 
—THE USE OF BENDS, ELBOWS, OUTLET AND JUNCTION 
BOXES.—DIRECTIONS FOR INSTALLING CONDUIT.—CON¬ 
DUIT JOBS AND THEIR ACCESSORIES.—SCHEDULE FOR 
WIRING SYSTEMS. 

Reasons for Employing Conduit.— Twenty years 
ago electric lighting had not impressed business 
men sufficiently with its advantages and practical 
value to represent anything more than an experi¬ 
ment. The dynamos were in a comparatively crude 
condition and their regulation imperfect. A very 
small portion of the city’s area was strung with 
electric wires, and in consequence thousands of 
poles and an aerial network greeted the eye, com¬ 
posed of electric light wires, high tension and low, 
telegraph wires and telephone wires. These wires 
crossed each other and frequently high tension 
currents poured into low tension lines, and the 
wiremen engaged in repairing circuits were often 
the subjects of tragic scenes. Deaths became so 
recurrent through confusion and accident that the 


AND SWITCHBOARDS 


12 5 

municipality decided to pass laws to avoid future 
trouble and demand that all wires be put under¬ 
ground. One of the first to observe this law long 
before it was passed, due largely to the necessity 
of the occasion, was the Edison Lighting Com¬ 
pany. It placed its wires underground in iron pipes 
and employed junction boxes and outlet boxes, in 
what was perhaps the first underground conduit 
system in New York City and in all probability in 
the United States. The repeated fires attributed 
in many cases to electric light wires brought the 
attention of the Fire Underwriters to residences, 
business houses, and public buildings with the re¬ 
sult that much wiring already installed was con¬ 
demned and a new code of rules framed which in¬ 
cluded the use of what was then called “ interior 
conduit ” for house wiring. At first merely paper 
tubing soaked in asphalt was used, then the tubing 
was armored with brass, and finally further pro¬ 
tection was sought against mechanical injury by 
the use of iron pipe conduit, at present greatly in 
vogue. 

Conduit Wiring. —The different kinds of wiring 
are included under the heads of 

1— Knob or insulator wiring. 

2— Cleat work. 

3— Moulding work. 

4— Conduit work. 

For exposed work the first three methods (Figs. 
43, 44, 45 and 46) may be employed although the 
third, moulding work, is the most ornamental of 


126 ELECTRIC-WIRING, DIAGRAMS 





Fig. 43. —Porcelain Cleats. 


Fig. 44. —Knob Insulator. 







Fig. 45. —Cleat Carrying Wires. 




Fig. 46.—Moulding Carrying Wires. 







































AND SWITCHBOARDS 


• 127 


the three. The last, conduit work (Fig. 47), is 
done either exposed or concealed. If exposed, as 
is the case in the railway stations connected to the 



Fig. 47.—Conduit Carrying Insulated Wire. 


electric elevated service of New York City, no 
architectural difficulties present themselves; but 
where the work is concealed, questions arise of a 
more complicated nature. An old building or one 
recently constructed may be wired for electric 
lights and conduit installed. In this case the walls 
and ceilings must be grooved and the floors torn 
up, making an exceedingly expensive and trouble¬ 
some job for the contractor, attended with many 
risks. On the other hand the conduit may be in¬ 
stalled in a new building before the plasterers get 
to work. In this case the work can be done with 
comparative ease and facility and a corresponding 
cheapness in cost. In either case the plan of wir¬ 
ing must be carefully worked out on paper so that 
no delays are experienced on this score. Where 
conduit is used different diameters of pipe must be 
employed because of the varied diameters of the 
wires. There are many different kinds of conduit 
turned out by the principal manufacturers, but 
they may all be generally grouped under the head- 











128 ELECTRIC-WIRING, DIAGRAMS 


ings of Iron Armored Conduit, Brass Armored 
Conduit, Flexible Metallic Conduit, Flexible Non- 
metallic Conduit, Asphaltic paper, or composition, 
called Unarmored Conduit. 

The installation of a conduit system is practically 
equivalent to the equipment of a house with pipes, 
exposed or concealed as the case may be, through 
which wires are fished after the pipe work is com¬ 
pleted. The necessity for using conduit of the 
correct size need hardly be commented upon. The 
greatest difficulty will be experienced if the pipes 
catch or grip the wires when they are fished 
through, and it is imperative therefore to only use 
the correct diameters, leaving nothing to chance 
in this respect. It occasionally happens in tall 
buildings that when mains or feeders are pulled 
through a conduit having several bends enormous 
force is necessary. This may be due to a kink in 
the wire or the bends or elbows in the pipe. A wire 
may slip through a pipe easily, yet catch if an 
elbow or two present themselves. A liberal allow¬ 
ance in pipe diameter will obviate this and save 
time and necessarily labor and expense if consid¬ 
ered in advance in the wiring plans. 

The standard sizes of conduit are given with 
reference to the inside diameters of the different 
samples. The inside diameters of iron armored 
conduit as given by one of the foremost manufact¬ 
urers are as follows: 


AND SWITCHBOARDS 


129 


Iron Armored Conduit. 


Inside 

diameter. 

Outside 

diameter. 

Inside 

diameter. 

Outside 

diameter. 

tV 

•675 

T ^ 

1.90 

i 

.84 

I A 

2-375 

tV 

I.05 

4 

2.875 

To 

I - 3 I 

2| 

3 - 5 °° 


1.66 




This conduit is made of standard weight iron 
pipe and the same rules are followed in installing 
it that relate to wiring in general. Whenever dif¬ 
ferent sizes of wire are to be connected a cutout 
must be installed and the circuits therefor radiate 
from or converge to panel boards. This is entirely 
in line with any other system of wiring whether 
knob, cleat or moulding. The iron armored con¬ 
duit consists of iron pipe lined inside with insulat¬ 
ing material, either a bushing or a composition in 
the form of a paint or enamel. 

Enameled iron conduit is the name especially 
applied to iron pipe with an insulating enamel in¬ 
side. As a general rule manufacturers guarantee 
that their product will bend without breaking or 
cracking the enamel. The inside and outside 
diameters are as follows: 


9 












! 3 o ELECTRIC-WIRING, DIAGRAMS 


Enameled Iron Conduit. 


Standard size pipe. 
Inches. 

Actual internal 
diameter. Inches. 

Actual outside 
diameter. Inches. 

1 

2 

.62 

.84 

i 

.82 

I.05 

I 

I.04 

I - 3 I 


1 - 3 8 

1.66 

1 h 

I.61 

1.90 

2 

2.06 

2-37 

2 ? . 

2.46 

2.87 

3 

3.06 

3 - 5 ° 


The brass armored conduit consists of a compo¬ 
sition of compressed paper saturated with an in¬ 
sulating solution and then protected on the outside 
with brass sheathing tightly embracing the inner 
thicker walled tube of conduit proper. The sizes 
of this material are as follows: 


Brass Armored Conduit. 


Inside diameter. 

Inside diameter. 

T 6 -g- inch. 

J inch. 

| inch. 

1.0 inch. 

^ inch. 

inch. 

f inch. 

1^ inch. 


In choosing conduit for a job care must be made 
in the selection that the wire can be pulled through 















AND SWITCHBOARDS 


I 3 I 

freely, otherwise great difficulty will be experienced 
when this point of the work is reached. 

The asphaltic paper tube runs into smaller sizes 
than the others. It is called plain conduit and rep¬ 
resents the first type of tubing employed years ago 
for the protection of wires as a substitute or equiva¬ 
lent for moulding. The sizes are as follows: 


Asphaltic PXper Tube or Plain Conduit. 


Inside diameter. 

Inside diameter. 

J inch. 

i inch. 

tV inch - 

i| inch. 

| inch. 

inch. 

f inch. 

2 inch. 

f inch. 

2 \ inch. 


Unarmored like the above is the tubing called 
the American Circular Loom Conduit. It consists 
of woven insulating tubing, flexible in character 
and of great convenience in bridging over other 
circuits. It is used to a great extent for switch¬ 
board work and is extensively used for general 
wiring. Where wires are exposed and turns are 
to be made it finds ready application. Before the 
insurance laws became so far reaching and iron 
pipe was required, the flexible conduit enjoyed un¬ 
disputed supremacy in the commercial field. The 
inside diameters are given in the following table: 









13 2 


ELECTRIC-WIRING, DIAGRAMS 


Flexible Woven Conduit. 


Inside diameter. 

Inside diameter. 

| inch. 

J inch. 


§ inch. 

1 inch. 


\ inch. 

1^ inch. 


j inch. 

- w - 



In conjunction with the woven conduit there is 
also the flexible metallic conduit which is exten- 




Figs. 48 and 49. —Method of Securing Flexible Metallic Conduit. 


sively employed in wiring (Figs. 48 and 49). The 
sizes as regards the inside diameters are as follows: 


Flexible Metallic Conduit. 


Inside diameter. 

Inside diameter. 

yV inch. 

f inch. 

| inch. 

1 inch. 

i inch. 

i* inch. 
















AND SWITCHBOARDS 


i33 


With all metallic conduits whether flexible or not 
there a're employed junction and outlet boxes (Figs. 
50, 51, 52, 53 and 54). They are either round 



Fig. 50.—Bend. 





Fig. 51.—Coupling. 



lined or square lined and serve for the purposes in¬ 
dicated by the names; either to allow wires to pass 














134 ELECTRIC-WIRING, DIAGRAMS 


out for lamps, chandeliers, etc., in which case out¬ 
let boxes are used, or to act as boxes in which junc¬ 
tions are made between circuits, hence the title. 



Fig. 53.—Outlet Box. 



A unique combination of both wire and conduit 
in one has been introduced to the wiring world 
under the name of flexible steel-armored conduc- 








































































AND SWITCHBOARDS 


*35 


tors. The purpose of this invention is primarily 
to develop a system by which wires can be installed 
where an ordinary conduit system would be a fail¬ 
ure. The ease with which wiring can be installed 
when the conductors are so protected represents 
a saving in labor that relieves the problem of what 
might otherwise be regarded as unusual expense. 
Then in such cases where wires could not be 
safely or securely installed the application of this 
system becomes an absolute necessity. To quote 
from the manufacturers’ catalogue “ the flexible 
steel armored conductors (Figs. 55 and 56) are of 



Fig. 55.—Flexible Steel Armored Conductors. 


special value for use under conditions, which would 
make difficult, if not impossible, the installation 
of a conduit system. The steel armor affords ample 
protection against ordinary mechanical injury, and 








136 ELECTRIC-WIRING, DIAGRAMS 


conductors so armored can easily be drawn or 
fished into a building between partitions and under 
floors. In such cases no fastenings are required 



except at the outlets. When so installed, these 
conductors may be removed, if desired, as easily as 
the wires could be drawn from a conduit. The 
lead-covered, steel-armored conductors are of spe¬ 
cial value in damp places, such as breweries, dye 
houses, stables, etc., and are specially recommended 
with twin conductors for marine and underground 
work.” 

The conduit generally installed is held in place 
by means of fasteners or straps. 

The lengths of conduits are joined together by 
couplings. When the flexible conductors are twin 





















AND SWITCHBOARDS 


i37 


or three conductors their special adaptability for 
marine service becomes pronounced. They are 
generally made of stranded wires, that is, many 
fine wires together to give flexibility to the con¬ 
ductor. The sizes are as follows: 


Flexible Steel Armored (Sizes). 


Twin. 

Marine work. 

Single conductor. 

14 

14 Twin. 

IO 

12 

12 Twin. 

8 

IO 

10 Twin. 

6 

8 


4 

6 


2 



1 


The couplings for ordinary conduit work run 
through a variety of sizes extending from \ up, 
depending on the character of the conduit, whether 
iron armored, brass armored or flexible, etc. In 
addition, elbows are employed where bends or 
turns are to be made. The various elements of a 
conduit system can be included under the following 
classification: 









138 ELECTRIC-WIRING, DIAGRAMS 


Character of conduit. 

Accessories. 

Iron armored. 

Iron elbows. 

Iron couplings. 

Plugs. 

Lock nuts. 

Tees. 

Caps. 

Malleable iron unions. 
Straps. 

Brass armored. 

Elbows. 

Couplings. 

Straps. 

Plain unarmored. 

Elbows. 

Couplings. 

Straps. 


The flexible metallic conduit system calls for 
about the same accessories as the iron armored, 
the only difference being the flexibility of one in 
contrast with the other, and therefore the absence 
of elbows. Whenever special devices are to be 
employed, the manufacturers are only too happy 
to give full information and, if necessary, to make 
such changes or improvements as are required. 
Each conduit system calls for a special set of tools 
and it is necessary to possess experience and skill 
to properly install a conduit system and handle the 
tools relating to it. The time allowed for installing 
a conduit system of the concealed type is neces- 









AND SWITCHBOARDS 


I 39 


sarily limited by the fact that the plasterers follow 
the electrical workers. Such being the case little 
time is left to rectify mistakes; should they be 
discovered after the plaster has been laid the con¬ 
tractor will be put to considerable expense. In 
many important cases the plans are either drawn 
up or at least vised by a competent consulting en¬ 
gineer to facilitate the completion of- the work and 
rest the responsibility for it. 

There are many kinds of wiring which must be 
done to fulfill the requirements of the specifications. 
These specifications cover the character of wiring 
and the number of outlets as well as the purpose 
for which they will be used. 

The system of wiring to be employed is also 
specified and must be carefully planned out and 
observed in the subsequent work. 

WIRING SYSTEMS. 

Three-wire system, iron conduit, direct current. 

Two-wire system, iron conduit, direct current. 

Two-wire system, iron conduit, alternating cur¬ 
rent. 

Two and three-wire system, iron conduit, for 
direct and alternating current. 

The last system refers to a combination wiring 
plan, the wires protected in conduit, to be con¬ 
nected to either the three-wire system of the street 
service or a private two-wire plant in the building. 
A schedule can be prepared which will include the 


140 


ELECTRIC-WIRING, DIAGRAMS 


general method of wiring, the system of conduit 
work, the exact voltage to be supplied and the 
character of the current—whether direct or alter¬ 
nating. 


System. 

Schedule. 

Volts. 

Two-wire. 

No. of mains. 

No. of feeders. 

No. of risers. 

No. of sub-mains. 
No. of branches. 

no 


A more elaborate schedule can be worked out 
comprising all the details of a wiring proposition, 
but for general practical purposes the above is 
sufficient. 

According to an authority, from whose words 
the following definition and requirements are taken 
with reference to the purpose in view in using con¬ 
duits “The object of a tube or conduit is to facili¬ 
tate the insertion or extraction of the conductors, 
to protect them from mechanical injury, and as 
far as possible from moisture. Tubes or conduits 
are to be considered merely as race ways, and are 
not to be relied on for insulation between wire and 
wire, or between the wire and the ground.” Con¬ 
duits themselves must meet with certain require¬ 
ments before they can be considered fit or safe to 
use. 









AND SWITCHBOARDS 


141 

Although many types can be selected, the condi¬ 
tions for their installation and for governing their 
selection may be better understood with reference 
to the following limitations: 

GENERAL REQUIREMENTS FOR CONDUIT. 

I. The conduit between junction box and junc¬ 
tion box must be continuous; 

II. It must be continuous between junction box 
and fixtures. 

III. It must be composed of such material or 
be of such construction that neither the insulation 
of the conductor or the insulation within the tube 
itself will be ultimately affected or deteriorated. 

IV. The conduit must be of such material that 
it will resist the effects of heat; it must not ignite 
or burn through the overheating of fusion of wires 
within it. 

V. It must be strong and hard enough to resist 
blows of hammers, the action of saws, or the points 
of nails or screws. It must, in fact, be able to resist 
mechanical injury due to these causes without col¬ 
lapse or fracture. 

VI. It must be capable of being installed as a 
complete pipe or conduit system without conduc¬ 
tors so that all heavy work on the building can be 
completed before the wires are pulled through their 
respective tubes. 

It might be added with reference to these facts 
that the risk of installing more than one wire in a 


I 4 2 ELECTRIC-WIRING, DIAGRAMS 

tube is so great as to be, except where particu¬ 
larly specified, forbidden by the Fire Underwriters. 
Where specially approved steel or iron conduit is 
installed, permission to use twin conductors or two 
conductors in the conduit is a matter of discretion 
on the part of the authorities. When iron or steel 
armored conduit meets with the approval of the 
Fire Underwriters it must be able to meet such 
requirements as are embodied in the following 
chapter. 


AND SWITCHBOARDS 


I 43 


CHAPTER VII 

REQUIREMENTS FOR IRON AND STEEL ARMORED CONDUIT.— 
LAYING OUT A CONDUIT SYSTEM.—THE INSULATION OF 
CONDUCTORS.—MECHANICAL WORK.—INSULATING MA¬ 
TERIALS.-CONCEALED AND EXPOSED WORK.—INSULA¬ 

TION RESISTANCE. — GROUNDED WIRES. — SOLDERING 
SOLUTION.—A DISTRIBUTION SHEET FOR LAYING OUT 
WIRING. 

Requirements for Iron and Steel Armored Con¬ 
duit .— a. When the tube is grounded to one leg 
of the circuit and the wire to the other, the volatili¬ 
zation of all or part of the wire when it is “ burnt 
out ” must not injure the tube. 

b. The insulating protective coating inside the 
tube must not become soft at a lower temperature 
than 158 degrees F. (70 degrees C.). 

When water is boiled inside the tube it must not 
dissolve the constituents of the insulation but must 
remain in its original condition. 

c. The effect of immersion or soaking in water 
for a few days must not so affect the mechanical 
integrity of the insulating material that it becomes 
[weak and therefore useless. 

d. The insulation resistance of the tube must 
remain high, if the length of tube is bent and filled 
with water and a test made at the end of three 


144 


ELECTRIC-WIRING, DIAGRAMS 


days. The insulation resistance under these cir¬ 
cumstances between the metallic pipe and its con- 

'a 

tents must not fall below i megohm. 

In order to continue the remarks to be made in 
general about conduit, its requirements and its in¬ 
stallation it may be further stated that all conduit 
ends projecting must be filled with an insulating 
compound to protect its contents from moisture 
and deterioration. This practice must be followed 
out at the junction boxes as well, and particular 
attention must be paid to all joints which accord¬ 
ing to requirement must be made moisture-proof 
and air-tight. 

As regards the finishing of the ends of project¬ 
ing conduits, these must extend at least I inch be¬ 
yond the mortar or plaster because of the possi¬ 
bility of moisture and foreign matter otherwise 
entering the tube. If necessary, this projection may 
be subsequently cut down, but it must project at 
least ^ inch beyond the wall surface when said 
surface is finished. These requirements are en¬ 
tirely in line with the dictates of practice and 
reason and mean the avoidance of trouble, both 
with regard to the choice of conduit and its instal¬ 
lation. 

Laying Out a Conduit System.—In laying out 
the plans of a conduit system certain responsibili¬ 
ties rest with the architect as well as the consult¬ 
ing engineer or contractor. The demands made 
upon the contractor and consulting engineer relate 
to the mapping out of the work and its subsequent 


AND SWITCHBOARDS 


I 45 


installation. That of the architect relates to the 
provisions made in the construction for the recep¬ 
tion of the conduits in a convenient and practical 
manner. The architect’s duties consist, therefore, 
in making provision when preparing the plans of 
the building, for such ducts, pockets and channels 
as may be required for the conduits and the electric 
light and power lines they carry. 

Insulation of Conductors.—The great danger of 
grounds and short-circuits in buildings may be re¬ 
duced to a minimum if the general principle is 
followed out when installing wires of regarding 
their installation, however good, as non-existent. 
If wires are installed in buildings, whether in con¬ 
duit, moulding or on insulators as if they possessed 
no insulation, but were bare, then the precautions 
taken would be so far reaching that the risk of 
faults from grounds or poor insulation is negligible. 

Mechanical Work.—Too much stress cannot be 
laid upon the necessity for as perfect mechanical 
work as can be done. The details of soldering 
and connecting wires, the taping of wires and the 
proper method of securing the conduit—all of 
these belong to the field of purely practical work 
calling for experience and skill on the part of the 
employes. Efficiency can only be secured if every 
portion of the conduit and conductor undergoes a 
careful inspection during the development of the 
work and during its completion. The best point 
from which to start, whether the wiring or conduit 
is being installed, is the center of distribution. 

10 


i 4 6 ELECTRIC-WIRING, DIAGRAMS 


After one or many have been selected, by a care¬ 
ful examination of the conditions, then it is neces¬ 
sary to select the correct points at which the 
switches and cutouts controlling the different cir¬ 
cuits are to be placed. In order to render such 
positions accessible for ready handling in case of 
.short-circuits, grounds, breaks or other faults, panel 
boards are generally employed. These boards are 
miniature switchboards at which all the circuits of 
a part of a floor, or of one or two floors, converge. 
They are the sub-centers of distribution of a large 
building. 

Insulating Materials.—Perhaps one of the great¬ 
est problems in electric wiring has been the selec¬ 
tion of the correct insulating materials for electrical 
work. In order that an insulating material may 
meet with the proper consideration before trial it 
is necessary that it should be 

1. An insulator. 

2. Non-combustible. 

3. Non-absorbent. 

4. Non-hygroscopic. 

There are many insulators and insulating mate¬ 
rials now in use which are apparently immune from 
shortcomings in this respect, but a close examina¬ 
tion will reveal the fallacy which a rigid test would 
make certain*. In the wiring world insulating ma¬ 
terial is used for switchboards, insulators, and in¬ 
sulation of the following materials: Marble, slate, 
porcelain, glass, mica. 

The marble and slate are used for switches, panel 


AND SWITCHBOARDS 


147 


boards and switchboards. The marble is entirely 
used for switchboards. The mica is employed for 
the covering of cutouts and in a compressed form 
for sockets, etc. The porcelain and glass are em¬ 
ployed for general insulating purposes. The cov¬ 
ering of wires differs from this, in that it consists 
of rubber or gutta-percha, but the strict require¬ 
ments for insulation whether of wire, switches,, 
switchboard or other devices are not any too high 
where special work is to be done. 

Special Insulation. —In damp places, where mois¬ 
ture is constantly soaking in to all materials, such 
as dye houses, breweries, stables, pulp mills, laun¬ 
dries and acid manufactories, where fumes are ex¬ 
ercising a deleterious effect, special insulation is 
required on wires, which is described thoroughly 
in the following paragraph : 

The wire must have a solid insulating covering 
of at least of an inch in thickness, and this cov¬ 
ered with a strong and tightly fitting braid. It 
must be difficult to burn or ignite and must possess 
insulating power sufficient to show 1 megohm after 
exposure through submersion to the action of water 
for two weeks, at a temperature of 70 degrees F., 
or after three days’ exposure through submersion 
to the action of lime water and the passage of a 
current of 550 volts pressure for three minutes. 
It is necessary in addition to expose such wire to 
the direct action of those liquids or fumes to which 
it will be subjected. 

Concealed and Exposed Work. —Wiring that is 


i 4 8 ELECTRIC-WIRING, DIAGRAMS 


either concealed or exposed represents the two 
cases where the allowance of current for the wires 
is different for the same amount of lighting. By 
this is meant that a wire of a given number of cir¬ 
cular mils cannot carry as much current for con¬ 
cealed work as for open or exposed work. 

In exposed work the air freely circulates around 
the wire and its radiating power is not limited by 
being surrounded by conduit or moulding. Such 
radiation as generally occurs takes place through 
the insulation into the outer air: 


Concealed wires in conduit. 

Open work 

on insulators. 

Gau^e No. 

Amperes 

Gauge No. 

Amperes 

B.&S. 

allowable. 

B. & S. 

allowable. 

oooo 

218 

OOOO 

3 12 

ooo 

i8i 

000 

262 

oo 

*5° 

00 

220 

o 

I2 5 

0 

185 

I 

105 

I 

156 

2 

88 

2 

131 

3 

75 

3 

no 

4 

63 

4 

9 2 

5 

53 

5 

77 

6 

45- 

6 

65 

8 

33 

8 

46 

IO 

2 5 

10 

3 2 

12 

17 

12 

2 3 

14 

12 

14 

16 

> 



















AND SWITCHBOARDS 


149 


The relation of current to insulation resistance 
has also been established by law as regards in¬ 
surance. The insulation resistance of the mains, 
feeder branches, etc., must not fall below a certain 
figure of at least 100,000 ohms. The entire wiring 
installation must not represent less than the insula¬ 
tion resistance given in the following table: 


Amperes. 

Insulation 

resistance. 

Amperes. 

Insulation 

resistance. 

IO 

4,000,000 

200 

200,000 

2 5 

1,600,000 

400 

100,000 

5 ° 

800,000 

800 

50,000 

100 

400,000 

1,600 

25,000 


The manner of development of the table is quite 
evident after a slight examination of the relation¬ 
ship of the figures to each other. The basis is 4 
megohms for 10 amperes, which would mean a 
corresponding sub-division of the resistance for 
any other greater current. For 20 amperes the in¬ 
sulation resistance is one-half, for 50 amperes one- 
fifth, etc., as indicated. 

Many detailed requirements have been estab¬ 
lished by practice relating to the essential elements 
of a wiring equipment. They relate to such im¬ 
portant articles as switches, cutouts, fixtures, etc. 
As regards the last, particular attention must be 
paid to the question of insulation resistance, where 
the fixtures supply gas as well as electricity. In 












150 ELECTRIC-WIRING, DIAGRAMS 

this case the fixture is insulated from the gas pipes 
or ground connection by means of an insulating 
joint. The reqiiirements read as follows: “Insu¬ 
lating joints to be approved must be entirely made 
of material that will resist the action of illuminat¬ 
ing gases, and will not give way or soften under 
the heat of an ordinary gas flame. They shall be 
so arranged that a deposit of moisture will not de¬ 
stroy the insulating effect, and shall have an in- 
.sulating resistance of 250,000 ohms between the gas 
pipe attachments, and be sufficiently strong to resist 
the strain they will be liable to in attachment/’ 

Perhaps the most fruitful cause of grounds and 
short-circuits may be found in fixtures and sockets 
unless the utmost care is taken during their in¬ 
stallation to remove such possibilities by strict 
adherence to the observed code. 

Grounded Wires.—When it becomes necessary 
to ground wires, when lightning arresters are in¬ 
stalled or protective devices are employed for tele¬ 
graph, telephone, fire, district messenger, and bur¬ 
glar alarms or their equipment, the ground wire 
must be connected to a gas or water pipe and 
'connection made beyond the first joint by solder¬ 
ing. If such a ground connection is impossible a 
ground must be made by means of a metallic plate 
or a collection of loose wires or pipes buried in 
moist earth. The ground wire in this case must 
not be smaller than a No. 16 B. & S. and must be 
supported as though it were a high potential wire 
to the final earth connection. The protective de- 


AND SWITCHBOARDS 


I 5 I 

vice is of an electromagnetic character and saves 
the circuits to which it is connected from a sudden 
rise of current and pressure due to the crossing of 
signaling and message-conveying wires with power 
or electric light circuits. It is inclosed in a water¬ 
proof metallic case and is placed outside the build¬ 
ing, or if placed inside, the wire leading into it 
through the wall must be carefully protected by 
approved insulating bushing. A very useful solu¬ 
tion for soldering wires may be made up from the 
following formula. It is recommended that after 
use the joint be carefully wiped to remove all traces 
of the acid and thereby prevent subsequent cor¬ 
rosion : 


Solution of zinc saturated.5 parts. 

Glycerine.1 part. 

Alcohol .•.4 parts. 


The solution of zinc is obtained by taking a 6 
oz. bottle and half filling it with hydrochloric acid. 
Then slowly drop in pieces of granulated zinc until 
the ebullition ceases. The solution then obtained 
corresponds to the first item of the formula just 
given. The joint is first heated with a blow-pipe 
or soldering iron after being carefully cleaned to 
expose the bright metal and the solution is applied 
with a stick and the solder will immediately flow 
freely. 

A very good plan is to follow a certain system 
as regards the position of every light in the build- 





ELECTRIC-WIRING, DIAGRAMS 


x5 2 

ing. Such a plan may be embodied in the form of 
what could be called “ A Distribution Sheet ” on 
the following order: 


Distribution Sheet. 


Cutouts. 

Floor. 

No. of 
lights— 

1. 

No. of 
lights—2. 

No. of 
lights—3. 

Total lamps. 

Ceiling. 

Wall. 

Switches. 

Ceiling. 

Wall. 

Switches. 

Ceiling. 

Wall. 

Switches. 

2 

I 

O 

I 

I 

2 

O 

I 

O 

3 

O 

6 

I 

2 

1 

O 

0 

O 

2 

O 

3 

O 

I 

6 


3 












4 





• 







5 












6 












7 







• 





The idea of this sheet is to conveniently locate 
the position of all lights for ready reference and to 
hold the plan of the wiring in as explicit and con¬ 
densed a form as possible. The importance of this 
cannot be overestimated when the wiring of a 20- 
story building is considered with its numerous 
outlets. In order to facilitate the work an outlet 
sheet is convenient to use. It is of a much simpler 
character than the above and may be laid out in 
this form: 






































AND SWITCHBOARDS 


I 53 


Floor. 

Outlets. 

Purpose. 

I 

IO 

Lighting. 

2 

8 

Lighting. 

3 

6 

Lighting. 

4 

7 

Lighting. 

5 

5 

Lighting. 

6 

9 

Lighting. 

7 

2 

Motors. 

8 

3 

Lighting. 

9 

6 

Lighting. 

IO 

• 

4 

Lighting. 


In laying out the position of the conduit, the 
exact knowledge of the position of each outlet and 
junction box is a matter of great importance. Mis¬ 
takes in the wiring plan in this respect on a big 
job may mean considerable delay, confusion and 
expense. Both these sheets may be extended to 
cover any number of floors, and from them esti¬ 
mates can be prepared for future work as regards 
labor and material. 

It is often the custom to estimate on conduit 
jobs, whether open or concealed, as well as mould¬ 
ing and insulator work, at so much per outlet, or 
so much per lamp completely equipped. In any 
case a list of the material required must be pre¬ 
pared and the cost of labor, to form a clear con¬ 
ception of the absolute cost. The items to be 
included in this list are based upon the character 
of the work, whether insulator, cleat, moulding or 










154 ELECTRIC-WIRING, DIAGRAMS 


conduit. In each case various essentials are differ¬ 
ent, particularly when concealed work is done. 
In this case the estimate must cover the additional 
cost of labor involved in ripping up floors, grooving 
the walls and cutting out a place in the walls for 
panel boards. 

Panel Boards.—In general house wiring the cir¬ 
cuits are all led to a given point on one floor if the 
floor is small, or, if it is large, several of these 
points are employed at which panel boards are in¬ 
stalled. Panel boards are merely slate boards on 
which small switches are systematically 'arranged 
for the control of the branch circuits on the floor 
and on which the fuses controlling those branches 
are mounted. 

They are built for two and three-wire mains 
(Figs. 57 and 58) with branches on both sides of 


-O-O—j 

— r\ i 



-TM>rr~ 

pi 

1 



\. 

\f\ O ! 


¥ " kj cji 00 

_ °c: 

Ch 


—0— 0-0 

w ^ ^ 

-o-rv■ #0 0 < 

.r mn < 

* —O' Ol-CK> 

^ ^ |—1 u ' 

■rv-ry—do r\ 

1 v 

./—B--0L-0-0- 

-n-r-— 

.> ' 

u ut—00 

^ ^ |-IU kJ 1 

" V. 

w ui_, 0-0 

( 

< 

c 

• ' 

( 

) ( 
n 

’ U— OO 

) 

) 


FlG. 57,—Panel Board for Two-wire System. 












































AND SWITCHBOARDS 


*55 



Fig. 58. — Panel Board for Three-wire System. 


the mains. In the illustrations are shown two 
panel boards as described, one for a two-wire sys¬ 
tem with two wire branches, the other for a three- 
wire system with two wire branches. In many 
cases a main switch is also mounted so as to give 
control to the entire floor or section of the floor as 
the case may be. In many respects these panels 
might be aptly termed secondary switchboards as 
they control the circuits at the points of distribu¬ 
tion. 

UNDERWRITERS’ REQUIREMENTS REGARDING 
SWITCHBOARDS AND PANEL BOARDS. 

Switchboard: 

a. Must be made of non-combustible non-absorp- 
tive insulating material, such as marble or slate. 















































156 ELECTRIC-WIRING, DIAGRAMS 


b. Must be kept free from moisture, and must 
be located so as to be accessible from all sides. 

c. Must have a main switch, main cutout and 
ammeter for each generator. Must also have a 
voltmeter and a ground detector. 

d. Must have a cutout and a switch for each 
side of each circuit leading from board. 

Tablet and Panel Boards: 

The following minimum distance between bare 
live metal parts, bus-bars, etc., must be main¬ 
tained between parts of opposite polarity, except 
at switches and link fuses, as follows: 

When mounted on the same surface—0-125 volts, 
f inch ; 126-250 volts, ij inch. When held free in 
the air—0-125 volts, \ inch ; 126-250 volts, f inch. 

Between parts of the same polarity: 

At link fuses—0-125 volts, -J inch; 126-250 volts, 
f inch. 

At switches or inclosed fuses, parts of the same 
polarity may be placed as close together as con¬ 
venience in handling will allow. 

It should be noted that the above distances are 
the minimum allowable, and it is urged that greater 
distances be adopted wherever the conditions will 
permit. 

The spacings given first apply to the branch 
conductors where inclosed fuses are used. 

The spacings given second apply to the distance 
between the raised main bars, and between these 
bars and the branch bars over which they pass. 

The spacings given third are intended to pre- 



AND SWITCHBOARDS 


i57 


vent the melting of a link fuse by the blowing of an 
adjacent fuse of the same polarity. 

For further and more detailed reference to the 
requirements of the National Board of Fire Under¬ 
writers the National Electrical Code must be con¬ 
sulted. A copy of this may be obtained from the 
Fire Underwriters of any large city. 

The routine work of a wiring problem is plain 
sailing, but the difficulties and unexpected expenses 
arise when special positions are required for lights 
and switches. 


158 ELECTRIC-WIRING, DIAGRAMS 


CHAPTER VIII 

THE LIGHT OF INCANDESCENT LAMPS.—THE POWER CON¬ 
SUMED BY LAMPS PER CANDLE POWER.—CANDLE POWER 
AND COAL.—EFFECT OF LOW PRESSURE ON LIGHT.— 
EFFECTS OF GLOBES ON LIGHT.—SIZE OF ROOM AND 
NUMBER OF LIGHTS.—USE OF SIDE LIGHTS AND CHANDE¬ 
LIERS.—COLOR OF ROOM DECORATION AND THE LIGHT¬ 
ING. 


Light of Incandescent Lamps.—The importance 
of considering in its proper aspect the light of 
lamps of the incandescent type, is due to the re¬ 
lationship between voltage and candle power in 
these lamps. To obtain the maximum light from 
the minimum power is not so much an object as 
to obtain durability or lasting qualities in the lamp. 
As lamps grow old they deteriorate and the light 
grows dim, so that to obtain the correct candle 
power such an accession of power is required as 
to make the production of such light a most un¬ 
economical proceeding. The efficiency of a lamp, 
or the relation between the light it gives and power 
it consumes, are matters of the utmost importance 
not only in its construction but in its utilization as 
well. In speaking of power, both volts and am¬ 
peres must be considered, therefore, when greater 
or less voltage is supplied to lamps or when the 


AND SWITCHBOARDS 


i59 


percentage of the normal is below or above 100 
per cent., the power consumption and the candle 
power vary accordingly. Tables have been pre¬ 
pared by many manufacturers covering these feat¬ 
ures, but they generally relate to the ratio of 
candle power to watts. This is given in the form 
of a given number of watts per candle power, and 
the average lamp consumes from between 3 to 4 
watts per candle power. In the following table 
some figures are given expressing the relationship 
between light and power for a consumption of 
power which varies from 1 to 4 watts per cp.: 


Total Watts =64. 


Watts per cp. 

Total cp. 

1.0 

64.00 

1-5 

42.66 

2.0 

32.0° 

2 -5 

25.60 

3-0 

21.33 

3-5 

18.29 

4.0 

16.00 


The practical basis is about 3.1 to 3.5 watts per 
candle power and on this relationship of power to 
light the following lamps, their candle power and 
wattage are given: 







160 ELECTRIC-WIRING, DIAGRAMS 


Watts per cp. =3.1. 


Candle power. 

Total watts. 

IOO 

3 IQ 

5 ° 

J 55 

3 2 

99.2 

16 

49.6 

8 

24.8 


These figures are bound to vary after the lamps 
have been in use a certain number of days. After 
prolonged use the lamps appear smoky and give 
a poor and inefficient light, which is due to the 
increased resistance of the filament. But if more 
than the normal pressure is supplied the light 
though brilliant is in the end very expensive be¬ 
cause of the subsequently rapid injury to the lamp 
and its exceedingly poor return for the power. 
The normal .voltage of a lamp therefore changes; 
gradually rising as the life of a lamp goes on and 
thereby increases the watts per candle power and 
drops the efficiency lower. A lamp lasts much 
longer if the voltage is a little lower, and acts more 
satisfactorily as a light producer in the end as far 
as the expense for lamps is concerned. But the 
danger lies in the voltage being too low and the 
light too dim. Then the practical efficiency of the 
lighting plant is affected. If the drop in the wires 
cause this, the wiring is a failure, but if the dynamo 
pressure is too low it should be increased. As an 







AND SWITCHBOARDS 161 

illustration of the enormous practical importance 
of this fact in electric wiring and electric lighting, 
take a no-volt lamp of 16 cp. and run it below its 
normal pressure. Let the voltage be limited to 
about 104.5 t° 105.5 volts and measure the candle 
power. It will not exceed 12 cp. In other words, 
a slight reduction in voltage to the lamp means a 
great drop in candle power, and if ten or twenty 
thousand dollars are spent to obtain a certain 
amount of candle power and 25 per cent, is wasted 
by low pressure the remaining candle power is ob¬ 
tained at a heavy expense. The only item to 
counterbalance this is the saving in lamp cost. 
The saving in lamps must therefore be balanced 
up against the value of the lost light on such a 
basis. In all probability a 25 per cent, cut in candle 
power will not pay when compared with the cost 
of lamp renewals. Take a 1,000 light no volt plant 
at an estimated cost of $10,000. If 25 per cent, of 
the light is wasted in order to save lamp renewals 
then the light of 250 lamps, at a pressure of about 
106 volts, is practically thrown away. The cost 
of 1,000 lamps is about $200 at 20 cents apiece, or 
higher, as the case may be according to prevailing 
market rates. The value of the light of 250 lamps, 
if supplied outside, is at least $100 a month. Esti¬ 
mating the life of these lamps at 600 hours and 
burning them 5 hours a day, it would mean 130 days 
or about a four months’ steady run before they com¬ 
pletely failed. If run at a low voltage they might 
last longer and only mean renewals twice, instead of 
11 


162 electric-wiring, diagrams 


three times a year. The cost of this is about $400, 
which can be compared with the $1,200 worth of 
light thrown away by low voltage. If the coal pile 
alone is considered, it will be seen that the amount 
of coal required for 1,000 lights at 5 lbs. per horse 
power hour would be, on the basis of 12 lamps per 
horse power, as follows: 

If 12 lamps = 5 lbs. per hour, 
then 1,000 lamps = 83X5 = 415 lbs. per hour. 

On the estimate of 5 hours’ lighting a day the total 
weight of coal consumed amounts to 5X415 = 
2,075 lbs. or about one ton. This coal may cost 
various prices per ton, but if $4 is t^ken as a fair 
price for good coal, then the expense in this direc¬ 
tion amounts to about $1,200 for 300 working days 
in the year. Of this amount 25 per cent, or $300 
worth is systematically thrown away by the low 
voltage being employed to save lamp wear. Each 
lamp renewal costs $200, and it seems at the best 
all that can be done is to reduce the number of 
lamp renewals from three to two per annum. This 
means a saving of only $200 in lamps as compared 
with $300 worth of coal which is burned and 
wasted. The depreciation of the plant is not con¬ 
sidered nor the interest on the investment, nor 
the fact that the labor paid for each year could do 
the extra lighting without extra trouble, etc. An¬ 
other feature of the case is the fact that if the light 
is poor extra lighting must be done to supply the 
required illumination, as the practical basis for 


AND SWITCHBOARDS 


163 

ordinary rooms should be about 16 cp. for every 
50 or 75 square feet of floor space, depending upon 
the tone of the decorations and wall paper. The 
appended table, giving figures taken from the rec¬ 
ords of the largest manufacturers of lamps in the 
United States with additions by the author, shows 
the fall of efficiency with the voltage and the heavy 
reduction in the illuminating power of the lamp : 


Rate of 3.1 Watts per cp. 


Percentage of 
the correct lamp 
pressure. 

Percentage of 
the correct can¬ 
dle power. 

Watts con¬ 
sumed per cp. 

Candle power 
of a 100 cp. 
lamp. 

. 90 

53 

4.68 

53 

9 1 

57 

4.46 

57 

9 2 

61 

4.26 

61 

93 

6 5 

4.1 

65 

94 

69-5 

3 • 9 2 

69-5 

95 

74 

3 • 76 

74 

96 

79 

3-6 

79 

97 

84 

3-45 

84 

98 

89 

3-34 

s? 

99 

94-5 

3 • 22 

94-5 

100 

100 

3 • 1 

100 

IOI 

106 

2 -99 

106 

102 

112 

2.9 

112 

103 

118 

2.8 

118 

104 

124.5 

2 -7 

124.5 

105 

I 3 I • 5 

2.62 

I 3 I -5 

106 

138-5 

2-54 

138-5 


The figures show that in the case of a 100 cp. 
no volt incandescent lamp between the voltages 














164 ELECTRIC-WIRING, DIAGRAMS 


of 99 and 116.6 the candle power varies from 53 to 
138.5 or almost as 1 is to 3. 

The various types or shades and globes also 
govern the amount of effective candle power ob¬ 
tained. It is a well-known physical fact that the 
various colors of glass are more or less absorptive, 
and may reduce the amount of useful light to such 
a degree as to render useless efforts to better it. 
The following figures relate to this fact with re¬ 
spect to the globes and the degree of absorption: 


Character of glass. 

Percentage of wasted light. 

Ordinary pane glass. 

about 10 per cent. . 
from 10 to 15 per cent, 
from 25 to 40 per cent, 
from 25 to 50 per cent, 
from 30 to 60 per cent, 
from 15 to 30 per cent. 

Cut or pressed glass. 

Ground glass. 

Opalescent glass. 

Red glass. 

Blue glass. 



The depth of color in the glass is a prime factor 
in determining the degree of absorption. A great 
deal of candle power can be produced, and wasted 
by the use of poor globes, thus nullifying advan¬ 
tages of good wiring and regulation. 

Choosing Globes.—In choosing globes several 
points must be taken into consideration which 
might be tabulated in the following manner: 

1— Cost of globes. 

2— Diffusion of light. 

3— Degree of absorption. 















AND SWITCHBOARDS 


l6 5 


4— Artistic design. 

5— Fragility. 

By the use of a little common sense the selection 
of such important articles can be made with a defi¬ 
nite purpose in view. Many of the best looking 
globes are poor light transmitters and the con¬ 
verse. As a general rule the cost and design are 
the predominating factors, whereas the effective 
diffusion of the light and the degree of absorption 
are perhaps of more importance from an economical 
and practical standpoint in the long run. 

The area of the lighted room as well as the 
height of the ceilings next lead to the determina¬ 
tion of the answer to the question: “ How shall the 
lamps be distributed and how many must be used? ” 
Take a room 20 feet in length by 15 feet in width 
and 12 feet high. The floor area is 20 X 15 = 300 
square feet; and the wall area equals 15 X 12 X 2 = 
360 added to 20 X 12 X 2 = 480 or a total of 840 
square feet. In order to illuminate this room suc¬ 
cessfully side lights must be employed and a chan¬ 
delier. Allowing one 16 cp. lamp for every 50 
square feet, in the case of a parlor or drawing room 
a six-light chandelier is required. If side lights 
exclusively are employed the figures used with 
reference to the walls would be 100 square feet per 
16 cp. lamp or an allowance of about 8 lamps. 
When the lighting is divided up between the side 
lights and chandelier about four side lights and 
four chandelier lights are the best to employ. This 
would mean the utilization of about 100 cp. from 


166 ELECTRIC-WIRING, DIAGRAMS 


the chandelier after it passes through the globes 
and 130 cp. from the side lights if used exclusively; 
or a total amount of candle power equal to at least 
130 if distributed throughout the room. It is there¬ 
fore evident that the distribution of the light is of 
more importance than the quantity, and a great 
deal of power can be ineffectively used to light a 
room where one-half as much, consumed in prop¬ 
erly arranged lights, would give greater satisfac¬ 
tion. The absorptive power of the globes must be 
considered in practical lighting particularly where 
it is necessary to bring out decorative effects at 
night. 

If the general tone produced by the decorators’ 
art in fine apartments is blue, pink or red, the light¬ 
ing must be done by choosing positions and globes 
to augment this effect and not to produce a dis¬ 
agreeable impression through inattention to such 
details. If red, blue or other colored globes are 
employed and full illumination is required the lost 
percentage of light must be added in the number 
of lamps or the candle power of the globes. 

It is well for those desirous of making of wiring 
an art as well as a trade to study the requirements 
of the business and social world in order to succeed 
in meeting the demands they make upon the con¬ 
tractor. The great dry-goods and department 
stores, the public buildings, the theatres, the 
churches and the home—these are not easy prob¬ 
lems that relate alone to the putting in of wires. 
They call for greater knowledge, which in its high- 


AND SWITCHBOARDS 


167 


est form goes hand and hand with the dictates of 
art and fashion. To produce not merely light, but a 
uniform light is the main idea, and in great audito¬ 
riums a careful study of conditions is the only way 
of meeting with any degree of success. The candle 
power is dependent entirely upon the voltage and 
to keep this up to the standard as well as to control 
the groups of lights, or, in other words, to obtain 
control and regulation of the light with one or more 
dynamos in lighting plants, the switchboard has 
been universally adopted. 



168 ELECTRIC-WIRING, DIAGRAMS 


CHAPTER IX 

SWITCHBOARDS AND THEIR PURPOSE.—THE PARTS OF A 
SWITCHBOARD.—CONNECTIONS OF A SHUNT WOUND 
GENERATOR.—THE CIRCUIT BREAKER.—THE RHEO¬ 
STAT.—CONNECTIONS OF A COMPOUND WOUND GENERA¬ 
TOR.—FUSES.—CONNECTIONS OF TWO SHUNT WOUND 
GENERATORS AND SWITCHBOARD.—EQUAL PRESSURES 
FOR BOTH DYNAMOS.—THE BUS BARS.—BACK VIEW OF 
SWITCHBOARD SHOWING WIRING CONNECTIONS FOR TWO 
SHUNT MACHINES.—CONNECTIONS OF COMPOUND WOUND 
MACHINES SHOWING BUS BARS AND EQUALIZER BAR IN 
SERVICE.—OVER COMPOUNDING.—THE SERIES WINDING 
AND ITS PURPOSE. 

Switchboards. — As the switchboard represents 
the connections which are made to obtain con¬ 
venient control of the circuits and in the case of 
several generators to effectually combine and direct 
their output, it is supplied with switches, meas¬ 
uring instruments, circuit-protecting devices and 
regulating devices. These may be considered in 
their order— 

1— Switches, 

2— Meters, 

3— Circuit breakers, 

4— Rheostats, 

further additions being merely secondary acces¬ 
sories not required by the code. 


AND SWITCHBOARDS 


169 


A switchboard cannot be designed until the cir¬ 
cuits leading to and from it have been carefully 
drawn out so that the number of switches, meters, 
circuit breakers and rheostats are fully known. It 
is not the practice to put up a board and then 
attach the wires, because the stony character of 
the material calls for careful drilling, and in addi¬ 
tion, the size of the stone or marble slab must be 
determined from the apparatus to be attached to it. 
This can be obtained from the schedule or list of 
the circuits and the character of the generators to 
be connected. 

Connections of a Shunt Wound Generator.— 

The essential connections of a shunt wound gene¬ 
rator relate to the armature and field connections 
and the devices connected to them either for pur¬ 
poses of regulation, protection or measurement. 

As shown in the illustration (Fig. 59) the con¬ 
nections of a shunt wound generator call for a 
rheostat in series with the field circuit; a main 
switch which controls the entire current supply 
and the two essential measuring instruments, an 
ammeter and a voltmeter. The ammeter is in 
series with the main circuit and indicates the total 
flow of current. The voltmeter is in multiple with 
the main circuit and indicates the voltage at the 
switchboard. 

Protection.—The circuits are protected individu¬ 
ally by means of fuses and collectively by means of 
a circuit breaker. There is a main switch, which, 
when opened, cuts off all communication between 


170 


ELECTRIC-WIRING, DIAGRAMS 


the dynamo and lighting circuits. This is also 
fused and acts as a protective device, but the de¬ 
vice which is accepted as most reliable and con- 


VOLTMETER AMMETER 



Fig. 59.—Connections and Accessories of a Shunt Wound Dynamo. 

venient is the automatic electro-magnetic circuit 
breaker. 

Circuit Breaker.—An automatic circuit breaker 
consists of a helix of heavy copper wire through 
which the full volume of the current circulates. 
This helix attracts an iron core whose pull is re¬ 
sisted by a powerful spring. The magnetic pull 
and the spring balance each other under ordinary 
conditions. When a heavy short circuit occurs, the 
pull of the helix, and consequently of its core, be- 
































AND SWITCHBOARDS 


I 7 I 

comes so great that the spring is overcome and a 
latch gives allowing the main line switch to fly 
open. This switch is so constructed that it opens 
instantaneously and without arcing and acts as the 
most efficient circuit protector in daily practice. 

Rheostat. —The rheostat is in series with the field 
winding and the main line is tapped at both poles 
to supply it with current. An examination of the 
sketch will show that the field and rheostat in 
series, are together in multiple with the armature 
terminals, so that the regulation of the dynamo 
can be readily accomplished by following the con¬ 
nections and mounting the rheostat on the switch¬ 
board. The rheostats in general use for switch¬ 
board connection are of the enamel type, that is, 
composed of iron or composition wires buried in 
enamel and attached to a flat metallic frame with 
considerable radiating surface. They occupy little 
space and have added greatly to the equipment of 
the switchboard. 

Connections of a Compound Wound Generator.— 

The sketch (Fig. 60) shows a difference between 
the connections only in so far as the series winding 
is concerned. The same devices are in use, namely, 
a rheostat, a circuit breaker, a main line switch and 
meters to register current and voltage. The series 
winding also carries the total current of the lamps, 
and final connections must be made to this effect. 
On nearly all switchboards there is provided a 
pilot lamp, which gives the light or pressure 
straight from the dynamo, and in addition a ground 


172 


ELECTRIC-WIRING, DIAGRAMS 


detector which is merely a lamp with one leg 
grounded and a push button in circuit to show the 
presence of a ground. It is so constructed that 


VOLTMETER AMMETER 



Fig. 60. —Connections and Accessories of a Compound Wound 

Dynamo. 

both legs of the circuit can be tested. The switch¬ 
board of both machines can be so designed that 
the street service can be turned on by use of a 
double poled and double throw switch. The com¬ 
pound wound generator is almost exclusively em¬ 
ployed in private plants and for street railway work 
on account of its automatic regulation. 

Fuses.— The fuses in general use for switch¬ 
boards are of the approved non-arcing type. Fuses 































AND SWITCHBOARDS 


i73 


✓ 


of this character are surrounded by an envelope or 
tube of incombustible material, within which the 
melting or volatilization of the fuse may take place 
without the spattering of metal or the deposition 
of fumes on the polished switchboard. In total 

AMMETER VOLTMETER AMMETER 



Fig. 61.—Diagrammatic Connections of Two Shunt Dynamos in 

Multiple. 

these items comprise the essentials and accessories 
of an ordinary switchboard for a single shunt or 
single compound wound machine. 

Connecting Two Shunt Wound Dynamos. — The 
method of connecting two shunt wound machines 
in multiple is shown in the sketch (Fig. 61). A 




























































174 


ELECTRIC-WIRING, DIAGRAMS 


certain amount of care must be exercised, because 
both are generators of electromotive force, and in 
consequence conditions result which would be dan¬ 
gerous if disregarded when both machines are in 
operation. Both machines may run as follows: 

First—Both at equal pressure. 

Second—Both at unequal pressure. 

Third—One as a dynamo and one as a motor. 

In order to have both run at an equal pressure, 
first one is allowed to run until its emf. is correct, 
the switch of the other machine being open, then 
the process covers the following as regards the 
other. The second machine is brought up to 
speed and its pressure made to tally with the firsB 
machine. This is accomplished by means of the 
regulating device or rheostat, whose action is 
recorded by the voltmeter. By means of these two 
devices the pressures are made to correspond with 
great exactness, before the main switch from the 
second dynamo is thrown in. When both dynamos 
are of equal pressure the main line switch is thrown 
in and this immediately calls upon the two dynamos 
for power. If they are alike in construction the 
variation in load will not be very great, but this 
is not apt to be the case, and the pressure of each 
must be again regulated until they are approxi¬ 
mately correct. This is an operation requiring 
some skill and practical experience before it is 
done quickly and without risk. 

Unequal Pressures.—The risk mentioned is that 
due to the unequal pressures, which cause the loads 


AND SWITCHBOARDS 


i75 


on the machines to be unequal and thereby throws 
too much on one and too little on the other. This 
is apt to cause overheating of the armature and if 
sustained over a long period a possible burn-out. 
Another danger is present however, and this is due 
to the fact that one may run as a motor if its press¬ 
ure falls very far below the other. 

Under these circumstances the fields will remain 
as before, and the dynamo will continue to run in 
the same direction as a motor, because the current 
is now entering the armature in the opposite direc¬ 
tion. This experiment can be readily tried with a 
small experimental shunt dynamo. The machine 
may be used as a generator with separately excited 
fields. If a reverse current is suddenly switched 
into the armature it will continue to run in the 
same direction as a motor. In the sketch (Fig. 62) 
two bus bars are employed to which the main line 
switch is connected and from which the pressure 
at the generators is readily obtained. The entire 
regulation in the case of two or more shunt wound 
dynamos running in parallel consists in looking 
out for the equal distribution of the load by means 
of the regulating rheostats. In the sketch is shown 
the appearance of the switchboard with all the in¬ 
struments and switches mounted. Two push but¬ 
tons are used for testing for the pressure of each 
dynamo respectively. The bus'bars are also in 
evidence, and in this case they simply consist of 
solid bars of pure copper to which all three switches 
are joined by copper bars. 


176 ELECTRIC-WIRING, DIAGRAMS 


It is easy to see this connection in practice in 
the other sketch. First the two dynamo switches 
which convey the current from the dynamos to 



Fig. 62. —Front View of Switchboard of Two Shunt Dynamos in 

Multiple. 

the bus bars; then the main line switch through 
which the total current passes to the lighting or 
motor circuits. Each of the dynamo circuits has 
in series with it a circuit breaker, which protects 
the dynamo to which it is connected from an ab¬ 
normal load. 1 here are non-arcing fuses mounted 
on the switches as an additional protection. It is 
also possible to have but one circuit breaker in 
the main line and thereby dispense with the two 
used in connection with the dynamos, but indi- 































AND SWITCHBOARDS 


1 77 


vidual protection for each machine is by far the 
best policy in general switchboard design. The 
use of two voltmeters instead of one is also the 
best practice although not absolutely necessary. 

The rear view of the switchboard is shown in 
the next sketch (Fig. 63) with the connections to 



2ND DYNAMO ,. ' 1ST DYNAMO 

MAIN LINE 

Fig. 63—Back View of Wiring Connections of Two Shunt Dynamos 

in Multiple. 

the different devices on the face of the board. In 
all cases where a single voltmeter is used with 
push button contacts from each dynamo care must 
be taken that each pole is connected right or a 
short circuit will result at the voltmeter binding 
posts or poles. The main circuit from each dynamo 
12 






















































178 ELECTRIC-WIRING, DIAGRAMS 

runs through the ammeter in series with which is 
the circuit breaker as shown. Two conductors of 
flexible cable lead the current from each dynamo 
respectively into its controlling switch and thence 
into the bus bars. From the bus bars through 
the main switch the current is led out to the dis¬ 
tributing circuits. In this case the circuits on the 
different floors are not individually controlled from 
the switchboard. If it is necessary to do this, the 
switchboard becomes a little more elaborate and 
the switches controlling the different floors must 
be shown on the face and back of the board. 

The control of different floors by means of the 
switchboard is required in complete equipments. 
A case of this kind is exhibited in the illustration 
(Fig. 64) where six separate circuits, each with 
its main switch, compose one section of the switch¬ 
board. 

The back (Fig. 65) and front appearance are 
shown, with all apparatus mounted in its place, 
and all wiring connections complete. It must be 
understood that if there are many changes in the 
load the** switchboard will not help to regulate it. 
It only serves as a convenient place on which to 
group the different devices and at which to con¬ 
centrate all the principal circuits. If the variation 
of load due to changes in the number of lights on 
the different floors is very marked, it will be 
necessary to regulate by the rheostat as often as 
required. In some plants of this description this 
is inevitable and represents one of its greatest 


AND SWITCHBOARDS 179 

drawbacks. If this rheostatic regulation is not 
attended to, the load upon the machines will dis- 



Fig. 64.—Front View of Switchboard with Two Shunt Dynamos in 
Multiple, Showing Mains to Various Floors. 

tribute itself unevenly, and may affect their speeds 
if the difference in balance is too great. In this 
case an overload would result, on either one or 





































































180 ELECTRIC-WIRING, DIAGRAMS 


the other dynamo, and the circuit breaker will act, 
■cutting open that circuit, as the case may be. 



VOLTMETER 
SWITCH 
O- 


VOLTMETER 


VOLTMETER 



VOLTMETER 

SWITCH 




\ /AMMETER 
—Tg_JjLI 


AMMETER 


?\ 2 - 


CIRCUIT BREAKER 
Q 


ooj jo 
SWITCHES 


6 


ij yi ij y ij yi y yi 









RHEOSTAT 


0 6 
DYN. 
SWITCH 

O Q 


O O 

MAIN 

SWITCH 


ura 


3 


=0 




RC 


JIT BREAKER 
P 


0 o 

DYN. 

SWITCH 

O O 


'»- 



RHEOSTAT 


B.C I l 

B^C. 


Fig. 65.—Back View of Switchboard with Two Shunt Dynamos in 
Multiple, Showing Wiring Connections to Mains from Bus Bars. 


The only satisfactory way in which two gener¬ 
ators can be run automatically with safety under 
all reasonable changes of load, and still preserve 
the pressure at its proper value, is by installing 




































































































































AND SWITCHBOARDS 181 

two compound wound dynamos, and attaching - 
them in multiple to the switchboard as shown. 
Both shunt and compound wound dynamos are in¬ 
cluded under the technical appellation “ constant 
potential machines," but they differ from each 
other, as has been previously pointed out, in their 
field windings. One has merely the ordinary shunt 
winding, the other has also a shunt winding, but 
a series winding in addition. In fact a compound 
wound dynamo, as far as its windings are con¬ 
cerned, consists of a series wound and shunt 
wound generator with their windings, as it were,, 
superposed upon each other. 

The Equalizer.—The automatic regulation is ac¬ 
complished by the series coil, and it is therefore 
necessary when two machines of this type are 
connected in multiple to secure the correct action 
of each by means of what is commonly termed an 
“equalizer bar" (Fig. 66). This bar simply con¬ 
nects one brush of each dynamo to the correspond¬ 
ing brush on every other dynamo connected to the 
series coils. In the case represented only two 
dynamos are in multiple, and it will be seen that 
the equalizer bar in this case was from the upper 
brush of one dynamo to the upper brush of the 
other; but it will be noted that this upper brush 
also feeds into the series coil of each dynamo re¬ 
spectively. If this idea is carefully followed out 
the diagram will also show that the upper brush 
of each generator can send its current either into 
the series coil or into the equalizer bar. If the 


182 ELECTRIC-WIRING, DIAGRAMS 


potential at each of these brushes is alike, the 
equalizer bar carries no current; but if the pressure 
generated by one dynamo is a little higher than 

AMMETER VOLTMETERS AMMETER 



Fig. 66. —Diagrammatic Connections of Two Compound Wound 
Dynamos in Multiple, with Equalizer Bar Connected. 

the other, due to the fact that the speed of either 
one has diminished, or the load on one is greater 
than that on the other, then, current from this brush 
of higher potential, will flow through the equalizer 



































































AND SWITCHBOARDS 


183 


bar into the series coil of the other dynamo. The 
effect of this is to strengthen its magnetic field,, 
thereby increasing its electromotive force and in 
this manner augmenting the pressure until both 
machines in this respect are in equilibrium. But 
it is also evident that when one machine builds 
up the series coil of another in this manner, it is 
at the expense of its own, therefore as the press¬ 
ure of one machine rises, the pressure of the other 
machine falls until both are equalized. The equal¬ 
izer circuit should be closed before the other cir¬ 
cuits, and to accomplish this it is often the practice 
to either have a separate switch in this circuit, or 
to provide a longer blade to the middle of the 
switch shown, so as to close this first as described. 
The two main wires running across in the last 
sketch, are bus bars of heavy copper, and feed the 
main line, or supply current, to a variety of switches 
connecting with the various floors or circuits of the 
building. The equalizer should be of very low re¬ 
sistance, otherwise the drop through it may rise 
too high, if for any reason it ever carries a con¬ 
siderable volume of current. By having it of ample 
cross section, the regulation may be carried to a 
fine point. In large plants, where several thousands 
of amperes may be generated, a sudden variation 
in load will be the cause of a heavy current flow¬ 
ing, which might develop a heavy drop in the 
“bar,” if the resistance is not low. ‘For instance, 
a resistance of .001 of an ohm, with a current of 
100, 1,000 and 2,000 amperes respectively, means. 


i8 4 ELECTRIC-WIRING, DIAGRAMS 


a drop of T V> i and 2 volts. This is very much 
accentuated, if the resistance of the bar is more, 
which, in some instances, it is very likely to be. 

Series Fields.—The adjustment of the series coil 
is also a matter of the greatest practical impor¬ 
tance. The amount of current it carries may be 
too great or too small. If this is the case, it is 
now the practice to regulate with a shunt placed 
in multiple with the series winding, to vary the 
current within certain limits. 

This variation of the current is necessary be¬ 
cause in some instances the ampere turns of the 
series coil are too great. It is not practical to cut 
down the turns after a dynamo is completed, but 
it is very easy to shunt part of the current and 
thereby reduce the magnetic effectiveness of the 
series coils. The adjustment of the pressure of a 
compound wound dynamo is thus made possible 
within very fine limits by this means. When it 
is desirable to over-compound a generator, the reg¬ 
ulating of the resistance of this shunt is a rapid 
and practical process. In tests where the regula¬ 
tion of a dynamo is limited by specifications to a 
few volts, from no load to a full load of 500 am¬ 
peres, such adjustment as this is appreciated in a 
commercial as well as a scientific sense. 

Over Compounding.—A dynamo is said to be 
over compounded if the series coils more than com¬ 
pensate for t*he various losses in the way of drop 

in the armature and armature reaction. A dvnamo 

* 

is over compounded, so that it will generate enough 


AND SWITCHBOARDS 


185 

extra pressure to equal the drop experienced in the 
conducting wires. The theory of the compound 
wound dynamo fully covers this ground, yet it may 
be condensed into a convenient form under the 
following headings: 

% 

PURPOSE OF THE SERIES WINDING. 

First—To compensate for armature reaction 
which cuts down the useful lines of force. 

Second—To compensate for the drop caused by 
the armature current flowing through the armature 
winding. 

Third—When over compounding, to compensate 
for the volts drop in the main lines and feeders. 

Fourth—To provide automatic regulation for all 
loads. 

The over compounding may be from 5 to 10 per 
cent, of the normal pressure, but this is largely 
governed by the percentage of drop in the wiring 
system. The method of compounding in general 
is of importance with respect to the wiring propo¬ 
sition, for the reason that regulation at different 
points of load if ineffective will mean poor lighting. 
Where the entire plant must be installed, as well 
as the wiring, the selection of the dynamo, whether 
shunt or compound wound, cannot be intelligently 
made unless a full knowledge of the requirements 
of such a machine are in possession of the pur¬ 
chaser. It is advisable to select an over com¬ 
pounded machine and modify the degree of the 


186 ELECTRIC-WIRING, DIAGRAMS 


over compounding by manipulating the german 
silver shunt attached in multiple with the series 
coil. If the resistance of this german silver shunt 
is increased, the over compounding will increase, 
that is to say, more current will flow through the 
series coils. But if the resistance of this auxiliary 
shunt is diminished, then less current flows through 
the ^series coils and the additional voltage they 
are the means of generating is cut down. Under 
ordinary conditions a compound wound dynamo 
simply preserves externally a uniform pressure, but 
if the drop outside will not allow of this condition 
prevailing then over compounding is resorted to 
and the building up of pressure takes place ex¬ 
ternally, hand in hand with the increase of the 
load. 

Street Railway Plants.—Compound wound gen¬ 
erators are used exclusively in street railway power 
houses. In stations of this character a sudden 
change in load of from ioo to several thousand 
amperes is not an unusual occurrence, and for that 
reason the utter futility of installing any other 
class of direct current generators has been repeat¬ 
edly exemplified in the early history of street rail¬ 
way practice. The . compound wound dynamo is 
the only practical solution of the lighting problem 
for private plants and street railway service, and 
its automatic regulation. in well-designed machines 
leaves but little to be desired. In street railway 
service the large switchboards are well equipped 
with automatic circuit breakers to avoid burn-outs. 


AND SWITCHBOARDS 


187 


The compound wound dynamo particularly re¬ 
quires the installation of these devices, because 
when short-circuited all the effects of an abnormal 
load are in evidence and the pressure is preserved. 

Serious damage would result if this, at times of 
terrific strain, were not relieved by means of the 
circuit breakers. It is not alone the dynamo which 
is concerned in such a case but the engine as well, 
parts of which are apt to give or at least be per¬ 
manently affected by an abnormal load. 


188 ELECTRIC-WIRING, DIAGRAMS 


CHAPTER X 

GENERATORS EOR ALTERNATING AND DIRECT CURRENT LIGHT¬ 
ING.—CHARACTER OF LIGHTING DONE.—THE SWITCH¬ 
BOARD FOR TWO COMPOUND WOUND GENERATORS.- 

CONNECTIONS TO INSTRUMENTS.—SWITCHBOARD FOR 
CONTROL OF SIX FLOORS AND TWO ELEVATORS.—CON¬ 
NECTING TWO SHUNT DYNAMOS ACCORDING TO THE 
THREE WIRE SYSTEM AT THE SWITCHBOARD.—SWITCH¬ 
BOARDS FOR ELECTROLYTIC WORK. 

Switchboards.—The immense number and variety 
of the switchboards employed for electric light and 
power purposes for both alternating and direct cur¬ 
rent, require some classification with regard to the 
character of the lighting as well as the type of 
generator employed. The following headings may 
prove convenient in this respect: 


Switchboard Design. 
Character o} generators. 


1. One shunt wound dyna¬ 

mo. 

2. Two or more shunt 

wound dynamos. 

3. One compound wound 

dynamo. 

4. Two or more compound 

wound dynamos. 


Character of lighting. 

Low t tension arc and incan 
descent. 

Low tension arc and incan 
descent. 

Low tension arc and incan 
descent. 

Low tension arc and incan 
descent. 


AND SWITCHBOARDS 


189 


Character of generators. 

5. Two or more shunt 

wound dynamos con¬ 
nected for the three- 
wire system. 

6. Two or more shunt 

wound dynamos con¬ 
nected for a combina¬ 
tion two and three- 
wire system. 

7. One or more series dy¬ 

namos each with sep¬ 
arate circuit. 

8. One alternator single 

phase. 

9. Two or more alternators 

single phase. 

10. One or more alternators 
two or three phase. 


Character of lighting. 

Low tension arc and incan¬ 
descent. 


Low tension arc and incan¬ 
descent. 


High tension arc lighting. 

Low tension arc and incan¬ 
descent. 

Low tension arc and incan¬ 
descent. 

Low tension arc and incan¬ 
descent. 


The last class of generators are employed for 
power transmission at exceedingly high pressures 
and in this respect they are better known than as 
generators for electric lighting. 

To lay out the design of a switchboard, it is ab¬ 
solutely necessary to become familiar with all the 
requirements of practice and the apparatus em¬ 
ployed for that purpose. The low tension, direct 
current apparatus differs essentially from the high 
tension, direct and alternating current. The higher 
departments of switchboard design call for an in¬ 
timate knowledge of the subject, and the proper 
protection and control of circuits and the care of 
the generator, whether direct or alternating, is 


i 9 o ELECTRIC-WIRING, DIAGRAMS 

largely dependent upon the amount of skill shown 
in the construction of the switchboard. A variety 
of technical works are at the command of the reader 
and systematic visits to large power stations will 
soon develop a familiarity with the subject which 
will show the relationship existing between station 
management and switchboard design. 

A satisfactory method is to lay out the plan of 
the switchboard so that the marble or slate can be 
drilled to receive the instruments and switches. 



Fig. 67 .-—Front View of Switchboard of Two Compound Wound 

Dynamos in Multiple. 






































AND SWITCHBOARDS 


191 

These must then be carefully mounted and con¬ 
nected up according to the sketches of the back 
view. Errors can be readily corrected on the draw- 
ing board and the sketches must be carefully ex- 



Fig. 68 . Back View, Showing Wiring Connections of Two Com¬ 
pound Wound Dynamos. 

amined to detect errors before the board is drilled. 
In the series of sketches (Figs. 67 and 68) supplied 
many items shown are more or less arbitrary. 

For instance, having the switches in the upper 




































































































192 


ELECTRIC-WIRING, DIAGRAMS 


or lower part of the switchboard, using single¬ 
pole or double-pole circuit breakers, controlling 
all main circuits from the switchboards or where 
they are used, etc. (see Figs. 69, 70, 71 and 72). 


AMMETER, 



VOLTMETER. 


VOLTMETER 


D.P. CIRCUIT BREAKER 


f 


2 


cD o a> o 

Jb db ab db 

0 


() 

d dD 

ELEVATOR 8W. 
FREIGHT 


(> 

() 

dl) 

db 


DYN. SWITCH 

Q - ■ -- 


0= 


a 


o°°°o 





AMMETER 


SWITCHES 


« D. P. CIRCUIT BREAKER 


n n n n u n 


o o 

db db 


0 o 

db dl) 


00 00 

db db db db 


9 


a 


0 

< 

db 

<ll> 




0 

c > 

db 

db 


2 


(D o 


MAIN SWITCH 


DYN. SWITCH 


BUS BARS 


dJ> dl) 

=0 elevator sw. 

_ PASSENGER 
=0 


EQUALIZER BAR 


=o 


RHEOSTAT 


n 

VOLTMETER ( ) 
SWITCH^dj) 


EQUALIZER 
SWITCH 
J 


s 


VOLTMETER, 
dJ^SWITCH 


o°°°o 

° 

RHEOSTAT 


Fig. 69.—Switchboard of Two Compound Wound Dynamos 
Multiple. Switches of 6 Floors and 2 Elevators. 


111 


It will be found that the architects’ or consulting 
engineers’ specifications will govern all this. If 
advice is needed, a practical switchboard manu¬ 
facturer is the best man to consult. 

Panel Switchboards.—Not only instruments and 






















































































AND SWITCHBOARDS 


i 93 


switches, but finished panels can be obtained com¬ 
plete from the manufacturer. These panels are in 
themselves small switchboards although sold under 
the names of generator panels, rheostat panels, 



jr IG . 70.—Back View of Switchboard, Showing Connections to 
Equalizer Bar, Switches and Meters. 


load panels, feeder panels, fuse panels and blank 
panels. These panels are about 5 feet by 2 feet,, 
although the feeder and fuse panels are about one- 
half the length of the others. > 

13 






























































































































194 


ELECTRIC-WIRING, DIAGRAMS 


The generator panels are made for either a 
single generator or designed so that further addi¬ 
tions will allow of more than one generator to be 
run in multiple. The generator panel consists of 



Fig. 71.—Two Shunt Dynamos Connected According to the Three- 

wire System. 


measuring instruments, ground detector, circuit 
breaker, switch and generally a lamp and shade. 
They are made of a capacity of from 200 to 3,000 
amperes. A rheostat panel is used for the purpose 
of mounting the rheostat on its back, the contacts 


















































































AND SWITCHBOARDS 


i95 


and arm appearing in the front. The load panel 
carries voltmeter and ammeter; the voltmeter of 
the illuminated dial dead beat differential type; 
the ammeter also with illuminated dial. The volt- 



Fig. 72. —Back View of Connections of Two Shunt Dynamos Oper¬ 
ating on the Three-wire System. 

meter is mounted on a swinging bracket and is 
used: first, for measuring the potential of the bus 
bars; second, for measuring the difference between 
the potential of the bus bars and that of the dynamo 



























































































196 ELECTRIC-WIRING, DIAGRAMS 


about to be connected. When this last is being 1 
accomplished the voltmeter is swung out at right 
angles to the switchboard and the dynamo tender 
adjusts the rheostat until the voltmeter reads zero. 
When the differential voltmeter reads zero the 
generator switch is thrown in. Load panels are 
built of a capacity reaching from a few hundred 
to 15,000 amperes. The feeder panels carry am¬ 
meters, circuit breakers and switches. The circuit 
breakers may be single or double-pole, the am¬ 
meters one or many according to the capacity of 
the panel, which is naturally governed by the car¬ 
rying capacity of the switches. Only switches may 
be mounted in special cases on the feeder panels 
where many circuits must be accommodated in a 
limited space. The fuse panels are supplied with 
fuse holders and should carry protected fuses of 
the most modern non-arcing type. Their capacity 
ranges from 240 to 1,800 amperes and over, the 
fuses 60 to 450 amperes apiece. Where blank 
panels are supplied, either empty sections are to be 
filled out or a special purpose is held in view. 

The so-called direct current lighting and power 
switchboards, described fully in the bulletin sheets 
of the leading electrical manufacturers, are gener¬ 
ally limited to a pressure of 750 volts. The switch¬ 
board is built up by assembling the various panels 
and connecting together by means of flat bars of 
aluminum, copper or standard sized wires. The 
bus bars are supplied specially and provision is 
made in the panels for their attachment. The 


AND SWITCHBOARDS 


*97 


cheapness and convenience of this style of sectional 
switchboard has recommended it strongly to the 
attention of contractors and prospective proprietors 
of private plants. 

Switchboards for Electrolytic Work. — Genera¬ 
tors developing heavy currents for electrolytic 
work were left out of the list on account of the 
infrequency with which the design of a switch¬ 
board for that purpose arises. In a switchboard 
installed for this class of work switches were de¬ 
signed to carry 6,000 amperes apiece. In this case 
the switches can be single-poled because of the low 
pressure. Wherever connections are made the 
greatest care is necessary to secure a low resistance 
joint. Heavy copper bars are employed to con¬ 
duct the current from point to point. The back of 
the switchboard when finished was provided with 
triple copper bars, each bar slightly separated from 
its neighbor to give radiation whenever the current 
was conducted from point to point. Great copper 
refining and plating plants are equipped with 
switchboards of this character. 


198 ELECTRIC-WIRING, DIAGRAMS 


CHAPTER XI 

V 

PANEL SWITCHBOARDS.—STREET RAILWAY SWITCHBOARDS. 
—CONNECTIONS OF COMPOUND WOUND GENERATORS IN 
A POWER HOUSE TO SWITCHBOARD AND INSTRUMENTS.— 
LIGHTNING ARRESTERS.—THE PANELS AND THEIR FUNC¬ 
TIONS. — STATION FIRES THROUGH LIGHTNING. — THE 
GENERATING, FEEDING AND METERING SECTIONS. 

Panel Switchboards. —The panels composing the 
essential parts of a switchboard, such as the gener¬ 
ator panel, load panel and feeder panel, call for the 
further classification of switchboards with reference 
to these facts. 

In street railway service particularly the two 
great divisions of apparatus and parts of the 
switchboard are the generating section and the 
feeding section. Dividing the switchboard up into 
panels is convenient in a practical sense and very 
instructive from a technical standpoint. All the 
apparatus relating to the generator, covering the 
instruments previously named, are placed on one 
panel, as shown in the sketch (Fig. 73). When 
large switchboards are erected, the generator panels 
are placed on the right hand side, the feeder panels 
on the left. 

It is customary to place the load panels between 
the two. The illustrations readily convey this 


AND SWITCHBOARDS 


199 


idea, showing generator, feeder and load panels 
with the equipment supplied by the largest manu¬ 
facturers of electric light and power apparatus in 



the United States. The generator panels may be 
supplied with either one double-pole or two single¬ 
pole switches for the following reasons: If a double¬ 
pole switch is employed a current capacity of not 



































200 


ELECTRIC-WIRING, DIAGRAMS 


more than 600 amperes is allowable with this spe¬ 
cial design. When two single-pole switches are 
supplied the panel is constructed to have a current 
capacity of from 800 to 2,000 amperes. 

The ammeters on these panels are all made of 
a greater capacity than the panel as a whole. The 
possibility of a continued overload calls for the 
employment of ammeters reading as high as 50 
per cent, above the rated capacity of the panel. 



Where the generator panel has a double-pole switch 
mounted on it a double-pole circuit breaker is also 
employed. The load panel carries an ammeter 
and a voltmeter. This voltmeter is used to give 
the bus bar reading ordinarily or it is indispensable 
where another generator is to be put in multiple. 

















AND SWITCHBOARDS 


201 


In this case it acts differentially, giving the differ¬ 
ence between the pressure of the generator and the 
bus bars, as previously described. A recording 
wattmeter giving the total external consumption 



Fig. 75.—Feeder Panel 
(Front). 



Fig. 76.—Feeder Panel 
(Back). 


of amperes or watt hours is also connected below 
in many cases. The feeder panel (Fig. 74), with its 
single-pole switches and ammeters, circuit break¬ 
ers and lightning arresters (frequently mounted on 
the back), represents the distributing department 

























202 


ELECTRIC-WIRING, DIAGRAMS 


of a large switchboard. In street railway service 
this system of designing and connecting switch¬ 
boards has proved a matter of incalculable value. 
The front and back view of a feeder panel is shown 



Fig. 77.—Generator 
Panel (Two Circuit). 



Panel (One Circuit). 


DIF. VOLTMETER 

Q 

AMMETER 

Q 


WATTMETER 

In—1| 


Fig. 79.—Load Panel. 


(Figs. 75 and 76), with the lightning arresters in 
place. The appearance of a panel switchboard 
(Fig. 80) consisting of two generator panels (Figs. 
77 arid 78), one load panel (Fig. 79) and three 
feeder panels is shown, carrying out the idea of 





























AND SWITCHBOARDS 


AMMETER 

CIRCUIT BREAKER 

co 

H (A 

05 

AMMETER 

CIRCUIT BREAKER 

CO &>€=§ 

Ui 

n § o° £ 

^ i °^I 

(L 

DIF. VOLTMETER 

AMMETER 

q: 

LU 

f 0 
1 

r= 

AMMETERS 

CIRCUIT BREAKERS 

^=0 M &0=0 

J hi 

X 

5 

05 »s=e 

AMMETERS 

CIRCUIT BREAKERS 

TIT 

S. P. SWITCHES 

11 [I If 

•00=8 

1}0=0 

AMMETERS 

CIRCUIT BREAKERS 

s L 

h I e 

h *1- 

i>0=G 

I>8=0 

le=0 


203 


Fig. 80. —Panel Switchboard, Showing Relative Position of Generator, Load and Feeder Panels. 

































































204 


ELECTRIC-WIRING, DIAGRAMS 


placing the generator panels to the right, the feeder 
panels to the left, and the load panel (Fig. 80) be¬ 
tween. 

Street Railway Switchboard.—The ideas carried 
out by the preceding series of principles relating to 
switchboards are embodied in the illustration (Fig. 
81) showing the connections of three compound 
wound generators operating in multiple to feed 
a street railway system. The front view of the 
switchboard really represents two switchboards, 
which might be called the primary or generator 
board in compliance with the last proposition relat¬ 
ing to this classification; the other, the secondary 
switchboard, would necessarily be called the dis¬ 
tributing or feeder board. In many stations the 
upper one is mounted on a platform above the first 
with a passage way for the attendant. 

A new feature to the reader is the upper line of 
lightning arresters protecting the outgoing feeders. 
The entire wiring plan of this switchboard is laid 
out from the generators to the generator board and 
then to the distributing section. It is a well-known 
fact that in street railway service the trolley line 
is reinforced during its entire length at regular 
intervals by connection with a system of feeders. 
By this means the pressure is kept at its normal 
value along the route and the speed of the cars 
preserved. Both track and trolley line are de¬ 
pendent upon this feeding system, which does not 
materially differ from that employed for incandes¬ 
cent lighting. The apparent complexity of the 


AND SWITCHBOARDS 


205 


switchboard is entirely due to the multiplicity of 
•circuits. 1 he key to the situation is a careful study 
of the fundamental principles underlying the theory 


,GROUND WIRE 



Fig. 81. —Back View of Generator and Feeder Switchboard, Showing Dynamos 

in Multiple. 








































































































































































































































206 ELECTRIC-WIRING, DIAGRAMS 


and construction of switchboards. In street rail¬ 
way service particularly the conditions of “ drop” 
and “ leakage ” require constant study and atten¬ 
tion. The switchboard, as far as the generators' 
and feeders’ sections are concerned, is no more than 
a means of sending out a uniform potential all over 
the system. In this respect a street railway system 
is resolved down to a wiring proposition, with 
many feeders and necessarily many centers of dis¬ 
tribution. 

General Principles of Switchboard Construction. 

—The design of a switchboard, to be conducted 
intelligently, must cover the ground indicated not 
only by these and other sketches, but, in particular, 
the general idea that all designs must represent. 
These facts, as relating to that idea, are crystallized 
in the synopsis conveniently arranged for future 
reference found at the end of this chapter. 

Whether a switchboard be designed for direct 
or alternating current it would be wise to consult 
some such plan as the above before proceeding to 
lay out the apparatus and circuits. For switch¬ 
boards for incandescent lighting and street railway 
service a departure could not be made from the 
system indicated. 

Lightning Arresters. — Lightning arresters are 
employed for the protection of alternating as well 
as direct current circuits. The injury electric light 
and power circuits are exposed to under certain 
conditions are, first, short circuits; second, grounds. 

By means of the lightning arrester protection 


AND SWITCHBOARDS 


207 


against either of these breakdowns through light¬ 
ning discharges is afforded. The lightning arrester 
(Fig. 82) offers protection against a sudden rise 



EARTH 


Fig. 82.—Principle of the Lightning Arrester. 


of potential in the lines by the use of, first, an air 
gap; second, a dead ground. 

In well constructed lightning arresters the air 
gap can be so adjusted that a rise of voltage be¬ 
yond a certain anticipated value will bring about 
a discharge. The danger arising in lightning ar¬ 
resters is due to the possibility of arcing. This 
will, in many instances, take place after an enor¬ 
mous burst of potential, which, leaping the gap 
leading to the earth, provides a gaseous path for 
the current of the generator unless the insulation 
is perfect. When lightning strikes a station un¬ 
provided with adequate protection it may leap be¬ 
tween wires of opposite polarity, which wires, if 
Hear enough, will develop an arc. In several 











208 ELECTRIC-WIRING, DIAGRAMS 

notable instances it was believed that lightning: 
supplied the flame and the fire to destroy the sta¬ 
tion. A little consideration of the direct possibil¬ 
ity of a high pressure discharge causing an arc 
will readily account for the destruction of prop¬ 
erty which ensues. In such cases the station sup¬ 
plies the power with which to burn itself down. 
The line is therefore provided with a pressure 
vent whenever danger may arise through exposure 
to discharges of this character. This is merely an 
air gap leading to the earth. Where a lightning 
discharge possesses a very high frequency it is 
well known theoretically and practically that the 
apparent resistance of a copper wire becomes so 
great that an air gap is preferable. On some such 
lines as this lightning arresters are designed for 
the protection of light and power circuits. 

TABLE 


Principle of Switchboard Construction for Shunt and Com¬ 
pound Wound Dynamos. 


Generating section. 

Metering section. 

Feeding section. 

Switches. 

Differential volt- 

Switches. 

Circuit breakers. 

meter. 

Circuit breakers. 

Bus bars. 

Ammeters. 

Bus bars. 

Ammeters. 

Wattmeter. 

Ammeters. 

Voltmeters. 

Rheostat. 


Lightning 

arresters. 








AND SWITCHBOARDS 


209 


CHAPTER XII 

TESTING. — THE GROUND DETECTOR. — TESTING WITH A 
VOLTMETER.—USE OF THE MAGNETO FOR TESTING 
INSULATION.—LOCATING GROUNDED CIRCUITS.—DAMP 
BASEMENTS.—USE OF INSULATORS.—WEATHERPROOF 
WIRE.—CABLES.—ROTARY CONVERTERS.—THE APPLI¬ 
CATIONS OF ROTARY CONVERTERS.—EFFICIENCY OF 
CONVERTERS. 

Testing.—Faults develop in electric light circuits 
and must be discovered and removed. The most 
flagrant sources of trouble are short circuits and 
grounds. 

Short circuits are caused by the crossing or 
touching of wires. Grounds caused by wires in 
contact with gas pipes are what is generally called 
a good earth connection. Breaks in the wires are 
evident when the lamps will not burn. Short cir¬ 
cuits or crossed wires cause the fuses to blow. 
Poor connections in the wires occurring where 
soldering between ends has taken place is due to 
the resistance of the joint. High resistance fre¬ 
quently is found where wires are held under screws 
and washers, as in cutouts, switches, sockets, etc. 

Operation of the Ground Detector.— For detect¬ 
ing heavy grounds, ground detectors are mounted 
on the switchboard. The ground detector for a 
14 




2io ELECTRIC-WIRING, DIAGRAMS 

two-wire and three-wire system operate according 
to the following principle: Two lamps are con¬ 
nected in series across the two main wires. The 
connecting wire between the two lamps is grounded 
by running a wire from a gas or water pipe and 
soldering it to this connecting wire. Under ordi- 



FlG. 83.-—Ground Detector for Two-wire System. 


nary circumstances when both wires are free from 
grounds the lamps burn with equal brightness. 
If the ground is on one leg of the circuit the lamp 
connected to the other leg burns more brightly, 
and vice versa. 

A switch is connected, as well as a safety fuse, 
between the earth and the two lamps. This switch 
is left open except when a test of this character 






























AND SWITCHBOARDS 


211 


is conducted. The illustration (Fig. 83) shows 
the general arrangement of the ground detector 
for a two-wire system with lamps, switch and fuse 
mounted. 



Fig. 84. —Ground Detector ior Three-wire System. 


In the next sketch (Fig. 84) is shown the gen¬ 
eral arrangement of.the wires in a ground detector 
for a three-wire system. 

If by any mistake both switches are closed at 
one time a short circuit will occur, because both of 
the outer legs are thrown into communication and 












































212 


ELECTRIC-WIRING, DIAGRAMS 


short circuited by that means. Therefore it is nec¬ 
essary to be careful in testing to open and close 
only one switch at a time and after using it to leave 
it open. 

The illustration shows how the fact of a ground 
occurring on either the neutral or negative wire 
will make the lamp on either the negative or neu¬ 
tral wire light up brighter than its neighbor. The 
same is true of the lamps connected to the positive 
and neutral wires. If a ground occurs on the 
positive wire the lamp connected to the neutral 
wire will light up brighter than its neighbor, and 
the reverse. The danger from grounds arises 
more from the risk of fire than anything else. If 
two wires of opposite polarity of the same circuit 
are grounded the leakage is in proportion to the 
resistance of each or both grounds. 

In street railway practice the danger from 
grounds is found in the corrosion of pipes through 
electrolytic action. 

Testing with a Voltmeter. — The voltmeter is 
employed in about the same manner as the lamps. 
It is connected between the earth and one leg of 
the circuit. If the other leg is grounded current 
will flow up into the voltmeter from the earth or 
from the other wire into the earth. Whichever 
wire gives a reading indicates that the other wire 
is grounded. The grounds may be roughly classi¬ 
fied as high resistance grounds, low resistance 
grounds and dead grounds. A high resistance 
ground runs into thousands of ohms; a low resist- 


AND SWITCHBOARDS 


213, 


ance ground into hundreds of ohms and a dead 
ground means absolute contact between one wire 
and the earth through a gas or water pipe, etc. 
If the insulation is high the voltmeter will not 
read, but if medium or low the reading will be in 
proportion. 

Using the Magneto.—The magneto is more fre¬ 
quently employed for line testing than any other 
piece of apparatus. One wire from the magneto 
is connected to a gas or water pipe and the other 
to each wire of the circuit in turn. 

If the magneto rings, a ground is present on the 
other wire. This method of testing while generally 
employed is sometimes deceptive, because perfect 
insulation may provide certain electrostatic condi¬ 
tions which will cause the magneto to receive a 
return static discharge from the circuit which may 
cause it to ring. As this is more an exceptional 
than a common case due consideration may be 
made for it. Magnetos for testing are so con¬ 
structed by means of the winding that they will 
ring through 1,000, 5,000, 10,000, 15,000, 20,000 and 
35,000 ohms. They are made to ring through 
higher resistances than this and are marked accord¬ 
ing to their capacity in this respect. A ground 
which can be rung through by a magneto is* there¬ 
fore of the same resistance as the rating of the 
magneto or less. If an attempt is made to discover 
a ground in a heavily wound coil, such as the field 
coil of a dynamo by ringing a magneto through 
it, the experiment will be unsuccessful, for the 


214 


ELECTRIC-WIRING, DIAGRAMS 


reason that the rapid reversal of current from the 
magneto cannot penetrate the numerous turns of 
«the coil. 

This is due to self-induction and will make it 
appear by the silence of the magneto as though 
no ground were present. 

This fact is of importance in testing any circuits 
connected to inductive devices for grounds. 

Locating Grounded Circuits. — To locate a 
grounded circuit each branch must be tested syste¬ 
matically. This is accomplished by disconnecting 
each circuit from its cutout or from the panel 
board to which it is connected. By testing each 
one in turn the grounded circuit is sure to be 
located and then the wires may be examined to 
discover the cause. Abraded wires are often the 
cause. Defective insulation on the inside and out¬ 
side of the conduit is another. Moisture, corrosion 
and damp walls and plaster are a frequent cause 
of trouble. Wires touching on the parts of chan¬ 
deliers and fixtures must be regarded as among 
the chief causes of trouble and annoyance. The 
voltmeter is the most scientific and, therefore, the 
most accurate instrument to use for this purpose. 
Where the ground is heavy neither the voltmeter 
or magneto are required. Two lamps in series 
connected to the circuit in the following manner 
can be employed: One leg of the circuit is con¬ 
nected to the end wire of the two lamps and the 
other end to the earth through the medium of a 
gas or water pipe. This is repeated with the 


AND SWITCHBOARDS 


2I 5 


other leg of the circuit. The process is continued 
throughout every circuit until the fault is dis¬ 
covered. 

The magneto proves exceptionally valuable in 
locating breaks in a line. This is indicated by the 
magneto not ringing. Where the continuity of 
the circuit of a series arc light system is to be 
tested the two ends of the circuit are connected 
to the magneto directly and the test made. Poor 
connections at fuses will cause heating, frequently 
sufficiently high to melt the fuse. It is therefore 
best to examine the fuses before exploring the rest 
of the circuit for breaks. It is good practice to- 
test for grounds every day in order to avoid trouble.. 
In large hotels and apartment houses where the 
chandeliers and fixtures are continually handled 
breaks and grounds happen often enough to neces¬ 
sitate this requirement. 

Damp Basements.— The grounds in damp places 
are naturally apt to be frequent, due to obvious 
causes. It is not always best to install a conduit 
system in this case, but a knob insulator equip¬ 
ment with rubber-covered wires. Sockets of in¬ 
sulating material must also be employed and fuse 
blocks must be protected from exposure to damp¬ 
ness by boxing. 

Insulators. —The knob porcelain insulators and 
porcelain cleats in use for electric light wiring must 
be designed with reference to the mechanical strain 
to which they will be subjected as well as the in¬ 
sulating properties they are supposed to possess. 



216 ELECTRIC-WIRING, DIAGRAMS 


The glass as well as the porcelain insulators must 
be designed with reference to strength and insula¬ 
tion. The element of strength is secured by con¬ 
sulting the mechanical requirements in the way of 
proportioning the diameter, length, diameter of 
the hole or orifice to receive the wooden peg or 
screw, etc. The insulating power is obtained 
through its dependence on the nature of the mate¬ 
rial, the distance from the wire to the screw or pin 
and the extent of the hygroscopic power of the 
glass or porcelain. The materials employed are 



Fig. 85.—Single Petti- Fig. 86.—Double Pet- Fig. 87.—Triple 
coat Insulator. ticoat Insulator. Petticoat Insulator. 

too well known to require repetition and their 
hygroscopic power is something unavoidable, but 
means may be taken to improve the insulating 
power of the material by the following scheme of 
construction: 

The petticoat, that is to say, the part of the in¬ 
sulator which acts as a hood to the pin", may be 
doubled or tripled, as shown in the sketches (Figs. 
85, 86 and 87), so as to increase the distance the 
current must travel from the wire to the pin, 

























AND SWITCHBOARDS 


217 


through the film of dust or moisture which is 
bound to collect on its surface according to the 
weather and age of the insulator. Very often for 
high potential circuits of over 5,000 volts oil insula¬ 
tors are used. In these, the edge of the insulator 
is turned up forming a channel in which oil is 
placed to increase the resistance in the path of an 
escaping current. 

Weatherproof Wire. —This wire is used in places 
such as the name indicates, where the weather can 
get at it. The wire is made of a certain number 
of layers of braided cotton-covering soaked in a 
highly insulating compound. By this means insula¬ 
tion is obtained and protection against wet as well. 
In large cities where wires are mainly under¬ 
ground, in the form of lead-covered cables, differ¬ 
ent insulation is employed. But for electric light 
wires in the country, arc and alternating, and for 
street railway feeders, this wire is extensively em¬ 
ployed. 

Cables. —The manufacture of cables is an elabo¬ 
rate process and the coverings of the wires they 
contain are varied according to the system peculiar 
to that particular phase of the art. The copper 
conductors are frequently covered with rubber 
compound which insulates the wire from the lead 
sheathing. If the pressure they carry is high the 
insulation is thicker. It generally varies from 
about i to f of an inch. In the case of other cables, 
the conductor is wrapped around with tough paper 
soaked in an insulating compound which gives it 


218 ELECTRIC-WIRING, DIAGRAMS 


flexibility as well. A third class of” cables for 
electric light and power might be described as con¬ 
sisting of weatherproof wires incased in lead tub¬ 
ing. The woven covering of the wires in this case 
consists of a jute or cotton braiding saturated to 
excess with a black insulating compound which is 
supposed to resist moisture and not to deteriorate 
with age. It is imperative to have a lead sheath¬ 
ing so thick that porosity is absent, as that would 
invite moisture to enter and rapidly destroy the 
integrity of the cable. 

Rotary Converters. — The development of the 
wiring system of a large central station is in many 
respects due to the introduction of a variety of 
new appliances whose use has led to economic 
changes of immense benefit to the installation as 
a whole. Among the appliances or devices to be 
thus considered the rotary converter possesses a 
leading interest. It has without doubt caused a 
change in engineering and station methods of the 
most far-reaching consequence. A rotary converter 
is a composite dynamo and motor combined in one 
machine. If continuous current is sent into it an 
alternating current can be developed of two or 
three phase and, conversely, if an alternating two 
or three-phase current is sent in a direct current 
will be generated. In other words it is a trans¬ 
forming device which receives an alternating and 
gives out a direct, or receives a direct and gives 
out an alternating current. In order to obtain this 
elasticity of operation a single generator frame is 




AND SWITCHBOARDS 


219 


employed within which rotates an armature so 
wound that it can receive a two or three-phase 
current at one end or a direct current of from no 
to 550 volts at the other end. The large power 
stations whose object it is to transmit current for 
street railway power and lighting purposes can 
accomplish this object by the use of the rotary 
converter. In addition, all the generating units, as 
the phrase goes, can be installed under one roof 
and the power from this central station distributed 
with economy and efficiency from various points 
at which such power would be useful, called sub¬ 
stations. By erecting substations, whose function 
it is to transform and distribute the power, instead 
of building power stations a great element of ex¬ 
pense is removed and a satisfactory commercial 
solution is given to the problem of the distribution 
of power. 

Various Equipments. —Many plants have been 
installed of immense proportions, in which these 
machines for transforming alternating into direct 
and direct into alternating current were the means 
of bringing about investments of millions of cap¬ 
ital. The Niagara Falls Power Company now gen¬ 
erate and deliver 50,000 hp. to the various factories 
and work shops, hotels and houses in Niagara 
Falls and adjacent cities and towns. Over 30,000 
hp. is drawn from the main power station and con¬ 
verted into continuous current for operating the 
street railway lines as well as for light and power 
in the cities of Buffalo and Lockport. 


220 


ELECTRIC-WIRING, DIAGRAMS 


The leading power stations in Greater New York 
operate on the same general principle. In these 
main stations the process of developing the elec¬ 
trical energy is carried on, then the power as a 
high-tension, alternating current is sent to various 
substations in which it is transformed into a com¬ 
paratively low pressure direct current. Among 
the institutions to which reference is made may be 
mentioned the power plants and substations of the 
Manhattan Elevated Railway Company, the Metro¬ 
politan Street Railway Company and the Rapid 
Transit Company whose equipment for the tunnels 
is one of the greatest as well as one of the most 
elaborate in the annals of engineering. These de¬ 
velopments in electrical engineering are only pos¬ 
sible through the recognized efficacy of the “ rota¬ 
ries ” as they are called. 

Application of Rotaries.—Under the following 
headings the most important applications of the 
rotary converter are given as cited by the bulletin 
of the Westinghouse Company. 

I. It may be supplied with alternating current 
and will deliver continuous current. 

II. It may be supplied with continuous current 
and will deliver alternating current. 

III. It may be connected to alternating cur¬ 
rent mains and operate as a simple synchronous 
motor. 

IV. It may be connected to continuous current 
mains and operate as a simple continuous current 
motor. 


AND SWITCHBOARDS 


221 


V. It may be driven by mechanical power as a 
generator and develop alternating current. 

VI. It may be driven by mechanical power as a 
generator and deliver continuous current. 

VII. It may be driven by mechanical power as 
a generator and deliver both alternating and con¬ 
tinuous current at the same time. 

VIII. It may be connected to continuous current 
mains and deliver mechanical power from a pulley 
on the shaft and at the same time deliver from its 
collector rings an alternating current. 

IX. It may be connected to the alternating cur¬ 
rent mains and deliver mechanical power from a 
pulley on the shaft and at the same time deliver 
from its commutator a continuous current. 

Although generally employed for the purpose of 
transforming the character of the current and the 
pressure, converters can be operated in multiple 
or two of them can be connected so as to supply 
a three-wire system. 

Efficiency.—On account of the high efficiency 
of the rotary converter, as high as that of a dynamo 
or motor of equal size, the electric light and power 
problem has been, to a large extent, solved. The 
regulation and sparking are about the same as 
would be found in an ordinary generator of equally • 
good design. The Edison Company of New York, 
whose original plant was entirely composed of no 
volt dynamos operating on the three-wire system, 
has had in use for many years rotaries, by means 
of which one station can relieve another when 


222 


ELECTRIC-WIRING, DIAGRAMS 


overloaded, or can help to distribute equally the 
power from one generating center to another with¬ 
out the necessity arising for the erection of new 
power houses, except through the natural causes of 
greatly increased demand. 


AND SWITCHBOARDS 


223 


CHAPTER XIII 

IMPORTANT FEATURES OF ALTERNATING CURRENTS TO 
CONSIDER. — LOSSES IN A LINE. — INDUCTANCE EX¬ 
PLAINED. — INDUCTANCE WITH ALTERNATING CUR¬ 
RENTS.—RESISTANCE COMPARED WITH INDUCTANCE. 
—EFFECT OF RESISTANCE AND INDUCTANCE ON AN 
ALTERNATING CURRENT.—EFFECT OF CAPACITY ON AN 
ALTERNATING CURRENT. 

Important Features.— Alternating currents pre¬ 
sent a different class of phenomena when trans¬ 
mitted and transformed than that form of electrical 
energy termed direct. The frequency of an alter¬ 
nating current, or the rate at which it moves back 
and forth in the circuit; the nature of the alternat¬ 
ing current wave, whether its growth is relatively 
rapid or slow; the resistance of the circuit and the 
degree to which magnetic effects can manifest 
themselves: all of these constitute important feat¬ 
ures (Fig. 88) in the consideration of alternating 
currents, requiring definition and elucidation. 

Losses in a Line. —Whenever electricity is trans¬ 
mitted from point to point, by the establishment 
of a circuit, certain losses are sustained and diffi¬ 
culties developed which may be classified as fol¬ 
lows : 

I. Losses in the line due to the current and re- 


224 


ELECTRIC-WIRING, DIAGRAMS 


sistance, included under the title of C 2 R or heat 
losses; and C X R or drop. 

2. Difficulties in the line, due to the rate at which 
the current reverses. 

] heat or cAr loss 

9 'FREQUENCY" EFFECT 


SECF INDUCTION 


LEAFAGE 


CONDENSER OR CAPACITY 3 4 5 EFFECT 


DROP OF PRESSURE 

^ —- 1 1 — ■ ■ ■ ■ ——————— 

Fig. 88. —Important Features of a Circuit Carrying Alternating 

Current. 


3. Difficulties in the line, due to the amount 
of magnetism or inductance developed along its 
length, or in certain parts of it. 

4. Waste of power, due to the deficiencies in the 
insulation employed around the wire, or on the 
insulators supported on poles. 

5. Difficulties due to the electrostatic effects in 
the line through its operation as a condenser. 

It may be stated at once that capacity or con¬ 
denser effects, in comparison with the effects of 
self-induction, produce opposite results. Thus, 
capacity encourages the free flow of current, while 









AND SWITCHBOARDS 


225 


inductance retards it. Neither the capacity or 
electrostatic effects, or the inductive effects are 
wasteful as far as the dissipation of energy is con¬ 
cerned Resistance wastes or degrades electrical 
energy, but not capacity or inductance. Resistance 
in a circuit develops heat if the current can operate 
conjointly with the pressure. When the current 
and pressure do not operate simultaneously, it is 
due to the effect either of self-induction or capacity. 

Inductance.—The rapid reversal of the current in 
any electric circuit means the rapid reversal of the 
lines of force v/ith which every circuit carrying a 
current is surrounded. No change can occur in the 
value of the current in a circuit without producing 
a proportionate change in the lines of force sur¬ 
rounding it. The mere fact that lines of force 
embrace a circuit, or, after embracing it, either in¬ 
crease or diminish in number, due to the increase 
or reduction of the current, means the development 
of an electromotive force, either instantaneously 
and then ceasing; or, due to a series of changes in 
the current value, lead to continued and corre¬ 
sponding electromotive forces through the said 
changes of current. In other words, the interlink¬ 
ing of magnetic lines of force with a circuit, which 
is inevitable when the current enters or leaves, 
causes an effect to be produced in the circuit called 
self-induction. It is an electromotive force (Fig. 
89) that opposes any increase of current in a cir¬ 
cuit, even when it first enters; and it likewise op¬ 
poses a discontinuation of the current when it is 
15 



226 ELECTRIC-WIRING, DIAGRAMS 


diminished or cut off. In the first instance, the 
current cannot enter at once at its full value; in the 
second instance, it cannot leave at once, but tends 
to continue flowing for a short period of time. 


DIRECTION OF 

E. M. F. OF SELF 
INDUCTION 


+ 

o- 


DIRECTION OF 

E.M. F. OF 
ENTERING CURRENT 


DIRECTION OF E.M.F. OF 

SELF INDUCTION WHEN 
CIRCUIT IS BROKEN 


DIRECTION OF E. M. F. OF. 
CURRENT WHEN CEASING 


o 


Fig. 89.—Opposing and Similar E M F of Self-induction Where 
Current is Made and Broken. 


An Alternating Current and Inductance.—These 
few words about inductance have a very important 
bearing upon a circuit carrying an alternating cur¬ 
rent. An alternating current not only alternates, 
that is, reverses in direction a certain number of 
times a second, but it consists of a number of waves 
following fast after each other, each wave moving 
in an opposite direction to that preceding or suc¬ 
ceeding it. At any given instant only one wave is 












AND SWITCHBOARDS 


227 


impressed upon the line, creating a positive and 
negative polarity. But an instant after, another 
wave, whose poles are opposite to the first, per¬ 
meates the circuit. Thus it is evident that each 
wave represents a growing value of the current 
(Fig. 90) until it reaches its highest point; and then 


MAXIMUM POINT 



Wa/e of E M F. 

a diminishing value, until it ceases to be. This zero 
point is the point at which a wave begins to grow 
reversely (Fig. 91) either in one direction or the 



MAXIMUM POINT 

Fig. 91. —Curve Showing the Rise from and Fall to Zero in a Single 
Wave of E M F in the Opposite Direction. 

other. And it is during these changes, in the rise 
and fall (Fig. 92) of the electrical energy in the 
line, that inductance plays its part. It operates in 
the circuit in such a manner that the tendency of 






228 


ELECTRIC-WIRING, DIAGRAMS 


the current to grow in value, as rapidly as it is pro¬ 
duced in the generator, is temporarily checked. 
The electromotive force, as it were, is already oper- 



MAX 


Fig. 92.—Curve Showing a Complete Cycle of EMF. 

ating upon the circuit, or, as the phrase goes, is im¬ 
pressed upon the circuit for a definite though short 
period of time before the current flows in response 
to its influence, and in proportion to the resistance 
of the said circuit. Even when it does flow, its 



Fig. 93. —Effect of Induction in Separating the Current and EMF. 


value, due to this condition of affairs, is neces¬ 
sarily checked (Fig. 93) the more—the more rapidly 
the waves act upon and leave the line. In other 
words, the faster the waves move back and forth, 
the greater the effects of inductance. 








AND SWITCHBOARDS 


229 


Inductance as Compared with Resistance.—The 
ohmic resistance of a line is distinguished from that 
resistance due to inductance by naming one resist¬ 
ance and the other reactance. It is perfectly evident 
that a conducting line made of copper can become 
deficient in conducting properties if it is exposed 
to the influence of so rapid a series of alternations 
that the reactance actually prevents more than a 
small percentage of the energy to pass. The resist¬ 
ance, therefore, is only one of the elements in a 
line, limiting the free flow of electricity. The addi¬ 
tional effects of the rapid reversals of current and 
the inductance or capacity must be considered in 
conjunction with the resistance. In a line em¬ 
braced by a given number of lines of force, the false 
resistance will naturally increase the more rapidly 
the current in each individual wave increases or 
diminishes. But the current in each wave or half 
alternation can only vary in value quickly if the 
wave itself is passing back and forth quickly. 
From this standpoint the greater the number of 
waves per second in any circuit the more rapidly 
the current rises to its maximum from zero, and the 
more rapidly it falls back to that point. Thus the 
frequency with which an alternating current passes 
back and forth is one of the fundamental reasons 
why the combined effects of resistance, inductance 
capacity, and this said frequency, produce more re¬ 
active effects. The more slowly the waves travel 
back and forth, the less is this influence a para¬ 
mount one. The name given to this combination 


230 


ELECTRIC-WIRING, DIAGRAMS 


of influences is impedance. It is a value which 
takes the place of ohmic resistance alone in cal¬ 
culations of current in circuits traversed by alter¬ 
nating waves of electrical energy. 

Effect of Resistance on an Alternating Current.— 
It may be distinctly stated that ohmic resistance 
has the same effect upon an alternating current as 
that experienced by a direct current. It reduces it 
in each case, as pointed out by Ohm’s Law. Al¬ 
though other secondary effects take place, they are 
distinct from those arising due to the length of 
the copper wire, its cross section in circular mils 
and its temperature. 

Effect of Inductance on an Alternating Current.— 

Another fact to be known is that inductance has 
the effect of retarding the flow of current entering 
a line. Its action is such- that the electromotive 
force tending to send a current through the cir¬ 
cuit is effectively opposed. This develops a con¬ 
dition similar to that existing through a higher 
ohmic resistance in the line. For this reason it 
is termed the reactance of inductance or induction 
reactance, and can be expressed in its equivalent 
in ohms. Inductance does not dissipate energy 
as ohmic resistance, but it affects the impressed 
emf . It is a secondary pressure, due entirely to 
changes taking place in the current. It acts to 
reduce the effectiveness of a current wave as far 
as the emf. of said wave is concerned. It will act 
in this manner when the current is rising from 
zero to its maximum value. As each complete 


AND SWITCHBOARDS 


231 


alternation consists of two waves it is evident 
that, although one sweeps through the circuit in 
an opposite direction to the other, there is a zero 
point to each from which the current rises to its 
greatest strength. During this growth of the cur¬ 
rent, inductance is operating against the impressed 
emf. The lines of force of the current have created 
it as an evidence of a change of current strength. 
This change is most emphasized when the current 
passes the zero mark. At this point it is not only 
diminishing until it disappears, but it reverses and 
grows in an opposite direction. The impressed 
emf., therefore, cannot deliver a current propor¬ 
tional to itself at once. An interval elapses before 
the current wave it is to pass through the circuit 
follows after it. This is called the lag of the cur¬ 
rent. It naturally becomes more emphasized as the 
inductance becomes more manifest. 

Effect of Capacity on an Alternating Current.— 
In a circuit with capacity the current leads. The 
emf. in this case follows after the current. In the 
case of inductance the current follows after the 
pressure. Instead of a weak and increasing cur¬ 
rent, as with inductance, there is a strong and 
diminishing current with capacity. The lag of 
the current behind the emf. in the case of induc¬ 
tance in the circuit, is replaced by a lag of the emf. 
after the current, in the case of capacity in the cir¬ 
cuit. In this case the current has “ lead ” instead 
of lag. Both inductance and capacity affect the 
value of the current, and the difference of phase 


232 ELECTRIC-WIRING, DIAGRAMS 


between the emf. and current. Inductance affects 
the circuit, with an entering current, as though 
a greater resistance were present; capacity affects 
a circuit with an entering current as though a 
lesser resistance were present. Capacity therefore 
produces the effect of less resistance, but not less 
than the ohmic resistance itself. The value of ca¬ 
pacity in connection with inductance, is its effect 
in reducing the inductance. In other words, in¬ 
ductance and capacity are the antithesis of each 
other in circuits traversed by alternating currents. 
When present in a certain relationship one de¬ 
stroys the effects of the other. 


AND SWITCHBOARDS 


233 


CHAPTER XIV 

CALCULATION OF REACTANCE.—VALUE OF INDUCTION RE¬ 
ACTANCE.—VALUE OF CAPACITY REACTANCE.—CALCU¬ 
LATION OF IMPEDANCE IN A CIRCUIT.—THE UNIT OF 
SELF INDUCTION.—THE POWER FACTOR. 

Calculation of Reactance.—The calculation of the 
two reactances, due to self induction and capacity 
in the circuit, is given in terms of the frequency 
and henries of inductance for the induction react¬ 
ance ; and in terms of the frequency and capacity 
in farads for the capacity reactance. Both may 
be given numerical values which can be used in 
obtaining results for circuits through which an 
alternating current passes, conforming in the char¬ 
acter of its waves to those falling within the scope 
of the formulas. 

Value of Induction Reactance. — Although the 
frequency of an alternating current may be given 
in reversals or waves per second, the calculation 
of the induction reactance calls for the multiplica¬ 
tion of this value by a quantity equal to 2 iror 2 X 
3.1416 equal to 6.2832. The result of this will be as 
follows: 

Where f = frequency or complete alternations per second, 
7T = 3.1416, 

L = inductance in henries of circuit, 
then the reactance due to the self induction and frequency 
will be 2 X ^ X f X L = 6.2832 X f X L. 


234 


ELECTRIC-WIRING, DIAGRAMS 


Example.—If the inductive reactance is to be 
calculated for a circuit, having a self induction of 
5 henries, through which an alternating current 
passes of a frequency of 125 per second, then the 
reactance = 6.2832 X 125 X 5 = 3927. 

This value represents the equivalent of an equal 
number of ohms with an increasing current in the 
circuit, but it will not dissipate nor degrade energy 
during its development in the said circuit. 

Value of Capacity Reactance.— Reactance caused 
by capacity is calculated in terms of the frequency 
and farads. The value of the reactance is given 
by the formula: 

Capacity reactance = 1 v2 X^Xf XK 
where 7r = 3.1416 

f = frequency of alternations 
K = capacity in farads 

this gives a value of —— - * . ■ ■ to the reactance. 

6.2832 X f X K 


If a circuit has a capacity of t |-q- of a farad and 
the frequency is equal to 125 cycles a second, then 
the reactance will be: 


6.2832 X 125 X i-Jtj- 


1 7-854 = .127. 


In the application of this formula it is evident 
that the lower the value of the capacity the greater 
the reactance. For instance, if Iv = yj.Vo instead 
of yj-ff, then the reactance becomes greater, or 1.27, 
In other words, the greater the capacity of the 
condenser, or the greater the electrostatic capacity 
of the line, the less the reactance. But the less 




AND SWITCHBOARDS 


2 35 

the capacity, the greater the reactance. In fact, 
with a very small capacity, the reactance would be 
practically as great as though only inductance was 
present. If the capacity in a circuit = io micro¬ 
farads, or twVVoo' of a farad, and the frequency 
is 120 per second, then on the same terms the 
reactance would be equal to i 6.2832 X 120 X 
.000010, which is equal to 1.00754 = 132.6. In 
calculations of capacity reactance, the capacity 
must not be used in the formula as anything else 
than a fractional or decimal part of a farad. Micro¬ 
farads cannot be used as units but only as so many 
millionths of a farad. 

Calculation of Impedance in a Circuit.—The con¬ 
ditions developed in a circuit carrying an alternat¬ 
ing current are due to three distinct influences. 
These influences are combined together in produc¬ 
ing an impedance to the free flow of current. They 
consist of, first, the well known effects of ohmic 
resistance; second, the reactance due to inductance; 
and third, the reactance due to capacity. 

If the three are combined in the form of a simple 
formula the following is obtained: 

Impedance = 

y/ ohms 2 -f- (Inductive reactance — capacity reactance) 2 . 

The result obtained by calculation is what has 
been called spurious or false resistance, but it is 
merely the ohmic resistance and reactance acting 
conjointly. If, for instance, the resistance of a 
circuit —10 ohms, the induction reactance = 50, 



236 ELECTRIC-WIRING, DIAGRAMS 


and the capacity reactance = 30, then the result 
would be as follows: 

Impedance = 

/ 10 X io-j- (50 — 30) 2 'y/ 100 + 400 -y/ 500 

or 22.3. 

In other words, although the circuit has only 10 
ohms resistance due to the wire itself, the react¬ 
ances build its apparent resistance up to 22.3. If 
the capacity reactance was so low as to be neg¬ 
ligible in this case, the impedance would become 

-y/ 100 -f 2500, or about 51. It is readily seen that 
if the ohmic resistance of a circuit or line is very 
low, then the reactance is all the resistance ex¬ 
perienced by the current. For instance, if the 
resistance is only 5 ohms, then the square of 5 
compared with the square of 50 becomes less im¬ 
portant. If the line resistance is only 1 ohm, then 

-y/ 1 2500 is practically the square root of the 

reactance squared. In other words, when low re¬ 
sistance and high inductance exist, the resistance may 
be neglected. 

The Unit of Self Induction, the Henry.—Defini¬ 
tions of various kinds are given to express the 
meaning of the henry or unit of self induction. 
Though primarily caused by the development of 
lines of force around a circuit, either when the 
current is increasing or diminishing, a specific 
effect must be produced to entitle the circuit to that 
qualification. The circuit must be so constituted 







AND SWITCHBOARDS 


237 


that if the current increases or diminishes one am¬ 
pere in a second an electromotive force of 1 volt 
is thereby produced. By this is meant that the 
number of turns of wire, or at least the length of 
the wire, will be embraced, interlinked, or cut by 
a certain number of lines of force in a second. 
These lines of force, developed in the course of a 
second by the current changing to the extent of 
1 ampere, will operate upon the circuit, producing 
a degree of inductance called 1 henry and repre¬ 
sented by the letter L. In a circuit carrying an 
alternating current, the current and pressure wave 
consists of a start from zero, a rise to a maximum, 
and a fall to zero. During the rise from zero self 
induction is in opposition to the impressed emf. 
Also, during the fall from its maximum value to 
zero, the self induction tends to prevent the re¬ 
duction of emf. The case thus presents itself of 
an opposition to the impressed emf. during the rise 
from zero, tzvice during each complete cycle; also 
the tendency of the self inductive effect to prevent 
the impressed emf. reaching zero, twice during 
each complete cycle. Dividing a cycle up into four 
quarters of 90 degrees apiece, the first and third 
quadrants show a back pressure to the impressed 
emf., the second and fourth quadrants show a for¬ 
ward inductive pressure with the impressed emf. 
It is quite evident that this phenomenon will cause 
so great a gap, as it were, between the impressed 
emf. and current, if much inductance is present, 
that in wiring circuits and power lines the degree 


238 ELECTRIC-WIRING, DIAGRAMS 

to which this affects the total watts must be 
known. 

The Power Factor. — The degree of electrical 
separation between the emf. and current is measured 
by an angle. This angle represents a short period of 
time, also an angle with respect to the entire cycle 
of 360°. If it equals 90°, the circuit is not carrying 
a useful current. Each quadrant is 90° (see Fig. 
94) ; each half cycle 180°; and the whole cycle 360°. 



Fig. 94.—The 360° Representing a Complete Cycle. 


The pressure noted in a voltmeter or the current 
noted in an ammeter is not the highest value of 
either. As the lowest is zero, it is evident that the 
average or mean value must be between the two. 
The wattmeter, therefore, records the power pass¬ 
ing through it, not the product of the maximum 
value of the volts and amperes of the alternations, 
but the effective values. In direct current work, 
multiplying amperes by volts gives watts at once. 
In alternating current work, multiplying volts by 







AND SWITCHBOARDS 


239 


amperes is not enough, even though their effective 
values may be found. The emf. and current may 
not appear simultaneously in the circuit. They 
may differ in phase from each other by an angle 
called <f> (Phi) (see Fig. 95). If the two elements 



of power are separated from each other by quite 
an interval of time, then <f> is a large angle. If the 
time is very short, <f> is small. The reason why cf> 
is considered at all is because it expresses the de¬ 
gree to which the volts and amperes of the circuit 
cooperate. It is a measure, in a way, of the amount 
of inductance present. 

A Wattless Current.—In an non-inductive cir¬ 
cuit there is no </>; in a circuit with much induction, 
in fact too much, will indicate so great a lack of 
cooperation between E and C, that no power will 
be available, even though a high pressure and a 
large current are noted on separate meters. This is 
a case of a wattless current , and a comparison made 
between the true power and the apparent power 
would be readily discerned by means of what is 
called the cosine of <f>, or the power factor. When 









240 


ELECTRIC-WIRING, DIAGRAMS 


the emf. impressed upon the line and the current 
are so related through the absence of inductance or 
capacity that they operate simultaneously, then the 
cos. <£=1, or the power factor is at its highest 
value. If inductance is developed in the line, the 
cos. <f> is less than i; in fact, as the inductance is 
increased the value of cos. </> diminishes toward 
zero. 

This is simply a diagrammatic way of repre¬ 
senting the manner in which the lack of coopera¬ 
tion of E and C is made apparent. The less they 
cooperate, or the greater the lag, the more nearly 
the angle </> approaches 90°. In utilizing the power 
factor, the volts and amperes are multiplied to¬ 
gether and by the cos. <f>. 



Apart, through Induction. 

For instance, if the angle of lag is o°, then cos. 
<£ = 1, and EXCXi = EXC. But if the angle 
of lag = 90° (Fig. 96), then cos. <j> =0 and E X C 
X 0 = 0, or there is no power. Between these two 
limits of zero and 1, the power factor will vary for 






AND SWITCHBOARDS 


241 


every circuit carrying an alternating current. If 
the power factor of a circuit is not known, and 
there is pronounced inductance present, the exact 
value of the power is problematic. In circuits sup- 
plying current for light or power the presence of 
machinery or apparatus containing inductance may 
diminish the available amount of power. In the 
following table the value of the cosine is given 
corresponding to the angular values of o° to 90°: 


Value of the Cosine of </> from o° to 90°. 


Angle in ^degrees. I 

Cosine. 

Angle in degrees. 

Cosine. 

Angle in degrees. 

Cosine. 

Angle in degrees. 

Cosine. 

Angle in degrees. 

Cosine. 

Angle in degrees. 

Cosine. 

0 

1.000 

16 

.961 

3 2 

.848 

47 

.682 

62 

.469 

77 

.225 

1 

•999 

17 

• 95 6 

33 

.838 

48 

.669 

63 

•454 

78 

.208 

2 

•999 

18 

• 95 1 

34 

.829 

49 

.656 

64 

•438 

79 

.191 

3 

.998 

r 9 

•945 

35 

.819 

50 

•643 

6 5 

.422 

80 

.174 

4 

•997 

20 

.940 

36 

.809 

5 1 

.629 

66 

.407 

81 

.156 

5 

.996 

21 

•934 

37 

•798 

5 2 

.616 

67 

• 39 1 

82 

• I 39 

6 

•995 

22 

• 9 2 7 

38 

.788 

53 

.602 

68 

•374 

83 

.122 

7 

.992 

2 3 

.920 

39 

•777 

54 

.588 

69 

•358 

84 

.105 

8 

.990 

24 

• 9 I 3 

40 

.766 

55 

•574 

70 

• 34 2 

85 

.087 

9 

.988 

25 

.906 

4 i 

•754 

5 6 

•559 

7 1 

.326 

86 

.070 

10 

• 9 8 5 

26 

.899 

4 2 

•743 

57 

•545 

7 2 

• 3°9 

87 

.052 

11 

.982 

2 7 

.891 

43 

• 73 1 

58 

■53° 

73 

.292 

88 

■035 

12 

.978 

28 

.883 

44 

• 7 I 9 

59 

•5i5 

74 

.276 

89 

.017 

1 3 

•974 

2 9 

•875 

45 

• 7°7 

60 

• 5 °° 

75 

•259 

90 

.000 

14 

.970 

3° 

.866 

46 

•695 

61 

.484 

76 

.242 



15 

.966 

3 1 

•857 










16 





































2 42 


ELECTRIC-WIRING, DIAGRAMS 


CHAPTER XV 

CIRCULAR MILS FOR ALTERNATING CURRENT MAINS.—VALUE 
OF C FOR SINGLE PHASE CURRENTS.—CIRCULAR MILS 
CALCULATED FOR SINGLE PHASE CIRCUITS.—CIRCULAR 
MILS CALCULATED FOR TWO PHASE CIRCUITS.—CIRCU¬ 
LAR MILS CALCULATED FOR THREE PHASE CIRCUITS.— 
AVERAGE POWER FACTORS.—WEIGHT OF COPPER.—THE 

INDUCTION MOTOR.—SYNCHRONOUS MOTORS.-ROTARIES 

IN POWER TRANSMISSION. — ROTARIES IN ELECTRIC 
LIGHT STATIONS.—TWO AND THREE PHASE ALTERNA¬ 
TOR CONNECTIONS. 

Size of Wire in Circular Mils for Alternating 
'Current Mains. —The size of a conductor carrying 
an alternating current is calculated with reference 
to the power factor by the following formula: 

Circular mils = DXWXC-fpX E 2 , 

in which W = watts delivered, 

D = length of run, 

p = loss in line in per cent, of power delivered, 
E = volts between receiving end of circuit, 

C = 2,160 for direct current, 

but varies according to the following, for single 
phase, two phase and three phase currents: 

Value of C for single phase currents with power 
factors of the values given as follows: 

Power factors 100 95 90 85 80 

Value of C 2,160 2,400 2,660 3,000 3,380 


AND SWITCHBOARDS 


243 


Example. To find the current and circular mils 
required for a circuit delivering - 10,000 watts, at a 
pressure of 100 volts, of a run of 1,000 feet. 

Current = WxTvE where 
T = 1.25 for single phase, 

= .62 “ two “ 

= .72 “ three “ with a power factor of 80. 

For single phase, therefore, calling this power 
factor 80: 

Current = 10,000 X 1.25 -f- 100 
= 12,500 -- 100 
= 125 amperes. 

Circular Mils with Single Phase.—Circular mils 
for single phase are then calculated by the formula 
in which they are equal to D X W X C -f- p X E 2 
where 

D = 1,000 ft. = length of run, 

W = 10,000= watts delivered, 

C = 3,380 = constant employed with a power factor of 80, 

p = 10 percent. = loss in line in per cent, of power 
delivered. 

E 2 = E X E = 100 X 100 = 10,000 = pressure at the 
receiving end squared. 

D X W X C p X E 2 = 1,000 X 10,000 X 3,380 -MoX 

10,000, 33,800,000,000 

=-- = 238,000 circu- 

100,000 

lar mils, with 10 per cent, drop, representing a wire equal, 
to a No. 000000 B. & S. 

The above calculations for a single phase system 
of wiring can be applied to the finding of the cir¬ 
cular mils required for either a feeder, main, or 



.244 


ELECTRIC-WIRING, DIAGRAMS 


branch. In each case the constant C must be 
adopted according to the power factor of the cir¬ 
cuit. If, in the last case, the power factor was 90 
instead of 80, the constant would have been 2,660 
instead of 3,380. The circular mils would have 
been as follows: 

„. . .. 1,000 X 10,000 X 2,660 ,, 

Circular mils = - = 266,000, 

100,000 

instead of 338,000. The difference between the two 
results is due to the difference in the power factors 
of the hypothetical circuits respectively. 

Circular Mils with Two Phase.—The value of 
the current in a two phase circuit may be found by 
the formula W X T - 4 - E, where 

T = .62 for two phase circuits with power factor of 80, 

W = watts delivered, 

E = volts between the receiving ends of the circuit. 

If, for instance, 10,000 watts are to be delivered 
at a pressure of 100 volts over a run of 1,000 feet, 
then the current in any leg of the circuit would be 
10,000 X .62-7- 100 = 6200 100 = 62 amperes. 

Values of T with Different Power Factors.—For 
calculating the current in circuits of single, two 
and three phase circuits the following table, giving 
the values of T, will prove very useful with different 
power factors. It will be noted, that the variable value 
of T for the different cases specified, increases as the 
power factor diminishes. 



AND SWITCHBOARDS 


245 




Power factors. 



100 

95 

90 

§5 

80 

Value of T for single 
phase. 

1.00 

1.05 

I.II 

I - I 7 

1.25 

Value of T for two 
phase (4 wire). 

• 5 o 

•53 

•55 

•59 

.62 

Value of T for three 
phase (3 wire). 

•58 

.61 

.64 

.68 

.72 


By means of this table the value of the current 
in a three phase circuit, as well as a one or two 
phase, may be found, with circuit conditions giving 
a power factor of from 80 to 100. 

In the case of a three phase circuit, delivering 
10,000 watts at a pressure of 100 volts, the current, 
with a power factor of 80, would equal 10,000 X - 7 2 

100 = 7200 -T- 100 = 72 amperes. The constant 
.72 is taken from the table under the power factor 
80. If the power factor had been 85 or 90, etc., the 
constant corresponding would have been selected 
accordingly. 

A table by means of which the circular mils of 
any phase of current may be readily found is given 
in the following, under the title of “ Values of C.” 

In this, as well as in other instances, it has been 
found advisable, for the sake of simplicity, to present 
useful figures in a tabular form. The convenience of 
this method is discovered wherever arbitrary values 
are apt to be used, instead of those based upon correct 
scientific data. The values of C, it will be noted, in¬ 
crease with the diminishing values of the power factor. 




















246 ELECTRIC-WIRING, DIAGRAMS 


TABLE. 


Power factors of circuits. 



100 

95 

90 

85 

80 

Values of C for single 
phase circuits. 

2:mo 

2400 

2660 

3000 

338 o 

Values of C for two 
phase circuits (4 wire) 

1080 

1200 

* 33 ° 

1500 

1690 

Values of C for three 
phase circuits (3 wire) 

1080 

1200 

I 33 ° 

1500 

1690 


In this table may be found the constant which 
can be used in finding the circular mils of a two 
phase circuit by the formula: Circular mils — D X 
W X C -f- p X E\ Taking the last case of 10,000 
watts sent 1,000 feet at a pressure of 100 volts with 
10 per cent, drop and with a power factor of 90, 
then the size of wire equals the following: 

Circular mils of two phase (four wire) circuit = 

D X W X 1,330 v p X E 2 , 
where D = 1,000 ft., 

W = 10,000 watts 
C = 1,330 (see table) 
p = 10 

E 2 = 100 X 100 = 10,000. 

Circular mils = 1,000 X 10,000 X 1,330 -f 10X 10,000, 

= 13,300,000,000 -r- 100,000, 

= 133,000 or a No. 00 B. & S. with a 10 per 

•cent. drop. 

If the power factor is 85, then the constant be- 

















AND SWITCHBOARDS 


247 


comes 1,500 instead of 1,330, and the resulting size 
of wire larger as shown by the calculation : 

Circ. mils = 1,000 X 10,000 X 1,500 -f 10 X 10,000, 
or circ. mils = 15,000,000,000 -j- 100,000, 

= 150,000 or a No. 000 B. & S. gauge. 

Circular Mils with Three Phase. —Calculating 
the current and circular mils for three phase cir¬ 
cuits is as simple with the use of constants as in 
the case of single and two phase circuits. As al¬ 
ready stated, the power factor of the circuit governs 
the value of the constant. Assuming a power fac¬ 
tor of 90, in the case of 30,000 watts, sent a distance 
of 5,000 feet at a pressure of 1,000 volts with a 10 
per cent, drop, the current and circular mils would 
be as follows: 

Current in amperes = W X T E, where W = 30,000, 
T = .64 (see table giving values of T with power factor of 
90), and E = 1,000 : then 

Current in amperes = 30,000 X .64 1,000 

current in amperes = 19,200 -f- 1,000 = 19.2. 

The number of circular mils required will be 
equal to 

D X W X C -r- p X E 2 , in which the following values 
are found : 

D = 5,000 ft., length of the power line, 

W = 30,000 watts delivered at the farther end, 

C = 1,330 for (3 wire, 3 phase), according to table, 
p = 10 per cent. 

E 2 = 1,000 X 1,000 = volts at receiving end squared, 


248 ELECTRIC-WIRING, DIAGRAMS 


therefore the circular mils = 5,000 X 30,000 X 1,330 -r- 
10 X 1,000,000, 

circular mils = 199,500,000,000 -j- 10,000,000, 
circular mils = 19,950 or a No. 7 B.&S. gauge. 

A change of power factor will bring about an¬ 
other result. As, for instance, a power factor of 80 
instead of 90, which makes the constant (see table) 
1,690 instead of 1,330, and gives a result as follows: 

1 

Circular mils = 5,000 X 30,000 X 1,690 -r 10X 1,000,000, 
circular mils = 253,500,000,000 4- 10,000,000, 
circular mils = 25,350 or a No. 6 B. & S. gauge. 

Average Power Factors for Circuits. —The cir¬ 
cuits employed for lighting, power or combination 
work naturally have different power factors. 

1. For instance, in regular lighting the power 
factor will vary from 90 to 95 per cent. If syn¬ 
chronous motors are installed as well, the power 
factor may diminish, but it will average up between 
these figures. 

2. For electric lighting and induction motors the 
power factor will be lower, somewhere between 85 
and 90 per cent. The reason for the reduction is 
found in the inductance introduced into the circuit 
by the motors. 

3. Where only induction motors are operated on 
the circuit the power factor will fall again to a 
lower value, lying between 80 and 85 per cent. 

In calculations of the current in one, two and 

three phase circuits great care must be taken not 

■ 

to confuse the constants employed. The same care 


AND SWITCHBOARDS 


249 


must be exercised in calculating the circular mils 
of similar circuits. The advantage of knowing the 
current in the conductors is found in comparing 
the respective weights of wire needed for house 
lighting or power transmission in various instances. 

Weight of Copper. —After finding the size of wire 
in circular mils, its weight is readily determined 
in pounds from the table giving circular mils, re¬ 
sistance, etc., in fact, from the wire table direct, 
which will supply the information in pounds per 
thousand feet. A very simple and rapid way is to 
divide the circular mils by 62.5 to get the pounds 
per mile. For instance, a mile of No. 10 B. & S. 
copper wire of 10,400 circular mils = 10,400 -f- 62.5 
= 166 pounds of copper per mile. 

The Induction Motor. —This motor requires no 
exciter and will start from rest with a moderate load. 
It differs from the type called synchronous in that 
it is started on two or three phase circuits by means 
of specially constructed transformers, called auto¬ 
transformers (Figs. 98 and 99), which permit it to 
receive a low pressure when beginning to speed 
up. An ordinary two way switch will be sufficient 
to control the current when starting and stopping, 
in conjunction with the auto-transformers. When 
running idle, an induction motor takes only suffi¬ 
cient current to operate itself and supply certain 
inherent losses. 

It consists of a stationary Held or . stator within 
which rotates the part developing the mechanical 
power (Fig. 97) called the rotor. As the magnetic 



250 ELECTRIC-WIRING, DIAGRAMS 


field sweeps around, as it were, its influence upon 
the rotor is to pull it around as well. This is due 
to the development of induced currents in the rotor. 



Fig. 97.—Elements of an Induction Motor. 


in virtue of which a reaction occurs which mani¬ 
fests itself as rotation, giving it in consequence 
the name of induction motor. The ratio of the 
revolutions of the rotor to the revolutions of the 
stator, that is, of the rotating magnetic field it pro¬ 
duces, is a measure of the efficiency. If speed of 
field = B and speed of rotor = A, then if B = 1,000 
and A = 900, the efficiency equals 900-y 1,000 = 90 
per cent. 










AND SWITCHBOARDS 


251 


Rotors may be of the type called squirrel cage, 
or they may have collector rings. In both instances 
a starting resistance is supplied. This resistance 
cuts itself in and out automatically when the motor 
starts from rest. Where the rotor has collector 
rings, an external speed controlling resistance is 
employed. Wiring circuits of a two and three phase 
induction motor are shown in Figs. 98 and 99. 


AUTO TRANSFORMER OF 1 PHASE 



Fig. 98. —Connections of a Two Phase Induction Motor, Showing 
Connections of Auto-transformers to a Starting Switch. 


A single phase induction motor requires to be 
started either by hand, by machine, or by splitting 
the single phase by special means, so that it acts 
like a two phase current temporarily, until the rotor 
is up to speed. 

Synchronous Motors. —Recent development in 
this motor has made it very valuable in the improv¬ 
ing of the power factor of an alternating current sys¬ 
tem. It has been made self-starting through a com- 












































252 ELECTRIC-WIRING, DIAGRAMS 


pensator. It is essentially an alternator receiving al¬ 
ternating current in its stator winding and direct 
current in the spools or windings on the shaft. The 
direct current is supplied by a small generator. 



Fig. 99.—Switch Connections of a Three-phase Induction Mo¬ 
tor Showing Auto-transformers in Position. 


When running without mechanical load the 
power factor of the system can be regulated some¬ 
what by over-exciting the direct current field. 
Doing this gives the machine a condenser effect 
which has a tendency to pull the lagging currents 
forward nearer to the voltage wave. This in itself 
has a tendency to raise the voltage. 

Rotaries in Power Transmission.— In the accom- 






















































AND SWITCHBOARDS 


2 53 


panying sketch (Fig. ioo) is shown the wiring 
plan of a power transmission plant with rotary 
converters in circuit performing the function for 
which they were designed, viz., the transforma- 



Fig. ioo. —Elements of a Power Transmission Plant. 


tion of alternating into continuous current at the 
receiving end, and the transformation of low press¬ 
ure alternating into high pressure alternating by 
means of alternating current transformers at the 
transmitting end. The alternating current trans¬ 
former consists of a magnetic circuit embracing 
two coils, a high and low pressure coil. By means 
of this device (Figs, ioi and 102) the pressure and 
amperes are converted either higher or lower, the 
total watts, with the exception of those naturally 
lost during the process, remaining the same. The 
transformers are termed step up transformers and 
step down transformers according to the purpose 
involved in their design. 

The windings of transformers are in the same 












































254 ELECTRIC-WIRING, DIAGRAMS 


proportion as the electromotive forces they gen¬ 
erate. That is to say, if the primary winding re¬ 
ceives 40 volts and has 40 turns the secondary 
winding to give 8 volts must have 8 turns. This 


WINDING 5 TO 1 
PRESSURF 5 to 1 


PRESSURE 
80 VOLTS 


TURNS ON 
PRIMARY 40 



PRESSURE 
8 VOLTS 


Fig. ioi.—P rinciple of Transformer Winding. 


gives a ratio of 5 to 1, and is termed “ ratio of 
transformation.” 

Rotaries in Electric Light Stations. —The applica¬ 
tion of rotaries, as previously stated, has, in a meas¬ 
ure, solved the problem of power distribution with 


500 V. ALTERNATING 600 V. ALTERNATING 



8TEP UP TRANSFORMER STEP DOWN TRANSFORMER 

Fig. 102. —Step up and Step down Transformer in Service. 


reference to the use of sub-stations and the degree 
of assistance one large central station can give to 
other smaller stations in various parts of the city 
supplying the same circuits. The transformer and 
the rotary have been the direct means of bringing 



























AND SWITCHBOARDS 


2 55 


about a revolution in lighting methods in direct 
current stations. 

In the illustration (Fig. 103) is shown the ma¬ 
chinery employed and way in which rotaries play 
their part in regard to the generation of direct 


110 VOLT 110 VOLT 



Fig. 103. —Method of Distributing Power to Sub-stations as Em¬ 
ployed by the Edison Company. 


current and its subsequent distribution to a sub¬ 
station, if it represents a surplus of power or if the 
distant station is approaching a point of overload. 
In either case the system is of incalculable benefit 
as regards elasticity and economy. By adopting 
this system on a large scale the necessity for any 
other than a large central station disappears. It 
becomes the center or nucleus of a number of sub¬ 
stations, which distribute the electricity after re¬ 
ceiving it, through the medium of rotaries, to the 
outlying circuits in their vicinity. 

Two Phase Lighting System. —As this system 
relates to power transmission and electric lighting 
































































256 ELECTRIC-WIRING, DIAGRAMS 


it must be included as a method which practice 
has shown to be of leading importance. By means 
of two or three phase currents, as already stated, 
it is possible to utilize self-starting alternating cur¬ 
rent . motors. Formerly, all alternating current 
motors were started by some external means, such 
as an engine or a direct current motor, or a means 
was found, as previously mentioned, of developing 
in a simple alternating current, called a single phase 
current, the equivalent of two phases, by which 
an alternating current motor became self-starting. 
The two and three phase current, however, is 
generated and utilized because it may be used not 
only for electric lighting but for motors with¬ 
out any accessories in the way of starting devices 
making them fundamentally self-starting. The gen¬ 
eral plan of the connections of a two phase alter¬ 
nator to the four lines by which its power is trans¬ 
mitted, as given by the Westinghouse Company, is 
shown in the illustration (Fig. 104). The auxiliary 
field is obtained by transforming the alternating 
into direct current by means of a commutator and 
sending this current into the additional field wind¬ 
ing designated. 

The Three Phase System. —The plan of connec¬ 
tions relating to this system is also shown (Fig. 
105) with auxiliary field connections as in the 
two phase system. In addition to the ordinary 
winding the auxiliary winding is employed, giving 
rise to the expression “ composite winding.” The 
additional coil of the series transformer receives 


AND SWITCHBOARDS 


257 


AUXILIARY field 



4 . B, A, B, 


vJULOJLOJUUL/—i 




COMMUTATOR 


uuuuu 

jujuum SERIES TRANSFORMED 

JUUUUU 



COLLECTOR RINGS 


Fig. 104. —Diagram of Connections for Two Phase 

Alternators. 



AUXILIARY FIELD 


rvMiiamMilyn 



commutator 


UMM 

UMAX 


SERIES TRANSFORMER 


COLLECTOR RINGS 



ABC Fig. 105.—Diagram of Connections for Three Phase 

Alternators. 


17 



























































258 ELECTRIC-WIRING, DIAGRAMS 


a low potential current proportional to the main 
current. This current when rectified acts upon 
the field of the alternator through the auxiliary- 
winding. 

It depends upon whether the main purpose is 
electric lighting with motor circuits incidental, or 
whether it is entirely a power supply for motors 
as to the wiring at the switchboard for a two 
phase system. A choice may be made of two 
methods: 

First—All four-wire circuits if motors are the 
principal purpose. 

Second—All three-wire circuits if lighting is the 
main object. 

In the second case the three wires, A lt Bj and 
A 2 or Bj, A 2 and B 2 are tapped. Transformers are 
connected and the pressure lowered to the point 
required. 


AND SWITCHBOARDS 


2 59 


CHAPTER XVI 

TRANSFORMERS.-CONTAINING NUMEROUS DIAGRAMS 

OF TRANSFORMER CONNECTION.—SINGLE-PHASE, 
SINGLE-PHASE MULTIPLE, TWO-PHASE FOUR-WIRE, 

TWO-PHASE THREE-WIRE SECONDARY.-OPEN 1 

DELTA, THREE-PHASE, DELTA-DELTA, STAR-STAR, 

DELTA STAR, STAR WITH NEUTRAL.-TESTING 

DELTA CONNECTIONS FOR ACCURACY.-BOOSTING 

AND LOWERING VOLTAGES BY USING DELTx\-STAR 
CONNECTIONS.-VOLTAGE AND CURRENT RELATION¬ 

SHIP WITH VOLTAGE RATIO OF TRANSFORMATION 
EXPLAINED. 

\ 

Static or stationary transformers are an absolute 
necessity in the distribution and utilization of high 
voltage alternating currents. Without them or 
some equivalent apparatus it would be absolutely 
dangerous to life and buildings to carry the high 
voltage wires into ordinarily constructed dwellings 
or factories. 

They are both useful for raising and lowering the 
voltage. When used to raise the voltage they are 
termed step-up transformers. When used to lower 
the voltage they are termed step-down transformers. 
The same transformer can be used for either pur¬ 
pose. Fig. 106 is a diagram of the connections of 
a single phase transformer. 

If the ratio of transformation in this transformer 



26 o 


ELECTRIC-WIRING, DIAGRAMS 


was 20 :i, one hundred volts applied at the winding 
having the smaller would cause two thousand volts 
to be excited in the winding having the greater 
number of turns of wire. 

When the voltage is transformed the current in 
amperes is raised or diminished as the voltage is 
lowered or increased. Thus the low voltage wind¬ 
ing is always made with thicker wire than the high 
voltage winding. In Fig. 106 A is drawn with 


High Voltage 


0 



Fig. 106.—Single-phase Transformer Connections. 

heavy lines and is assumed to be the low voltage 
windings. If two thousand volts were impressed on 
B winding ioo volts would be available at A. 

In transforming voltages from one pressure to 
another there is a loss of electrical energy which 
in a well-designed transformer will be approximate¬ 
ly two per cent, when the transformer is working 
at its rated capacity. This loss is greater when 
the transformer is operating at partial loads. Thus 
if the coil to which the impressed voltage is con¬ 
nected absorbs twenty kilowatts, there will be avail¬ 
able at the transformed voltage coils twenty kilo¬ 
watts minus two per cent, of twenty kilowatts. 







AND SWITCHBOARDS 


261 


Thus it will be seen that the following will occur 
in a transformer whose ratio is 20:1: 

20 K.W. at 2,000 volts = 10 amperes of current. 
20 K.W. at 100 volts = 200 amperes of current. 
With the two per cent, inherent loss of the trans¬ 
former the kilowatt output would be less; thus, 


20 K. W. X (100 — 2) = 19.6 K. W. 


19.6 K. W. 


19.600 

-- = 196 amperes 

100 


The above is intended to show the reader in a 
clear, concise maner the results that will be obtained 
with the use of a transformer. When the voltage 
is transformed to a lower pressure the current out¬ 
put is correspondingly increased as the voltage or 
pressure is decreased. Also when the voltage is 
increased by means of transformers the current 
available at the increased pressure is correspond¬ 
ingly less. 

When connecting transformers the lower voltage 
winding can be easily distinguished from the higher 
voltage coils because of their heavier current car¬ 
rying capacity which involves a greater cross- 
section of copper or a larger diameter of wire. 

The connecting of transformers requires care and 
an exact knowledge of what one should do, as under 
some conditions it is possible for one to connect 
them together and not know that he has done any 
wrong until the transformers show signs of distress. 

On single-phase lines the connecting of trans¬ 
formers is a simple matter once the high and low 





262 ELECTRIC-WIRING, DIAGRAMS 


voltage windings are known. The connections are 
diagrammed in Fig. 107. 


High Voltage 



mm. 


vmr 


Low Voltage 


Fig. 107. —Primary and Secondary Connections of Single¬ 
phase Transformer. 

It is only when the transformers are connected in 
multiple or parallel on single-phase lines that there 
is any doubt of the result. Fig. 108 shows trans¬ 
formers in multiple. Before the connections are 


- i 

--*- 



jmma 


Msmsu 




imm' 



Low 

Voltage 


• 

A 


Fig. ic8. —Single-phase Transformers in Multiple. 

• 

made it is necessary to see that the transformer 
ratios are the same in all transformers to be con¬ 
nected in multiple. Also if the lines are alive or 
carry electrical energy to test the low voltage coils 
for instantaneous direction of flow of the current. 


























AND SWITCHBOARDS 


263 

This can be done by leaving the connection at A, 
Figure 108, open and testing with a voltmeter 
across the open connection. If the voltmeter does 
not indicate any voltage the instantaneous direc¬ 
tion of flow will be towards the open connection, 
both from the transformer and the interconnecting 
wire. This is as it should be and it is safe to close 
the connection at A. Should the voltmeter show 
a voltage existing at A, reverse the low voltage 
wires from the transformers at the interconnecting 
wires. 



Fig. 109.—Feathered Arrows Show Relative Instantaneous 
Directions of Primary and Secondary Currents. 

Figure 109 shows the instantaneous direction of 
flow of current as arranged in all commercial trans- 






























264 ELECTRIC-WIRING, DIAGRAMS 


formers. However, it is well to make the test as 
it is possible for a workman to make an error and 
connect the wires wrongly. 

There are twt> ways of connecting transformers 
to two-phase lines. One is similar to single-phase 
and is shown in Figure no. 


High Vo i tag e 


One Phase 






One Phase 




Mnstsb 


suulusl 






wmw 


One Phase 







One Phase 



Loiv Vo'tags 


[Fig. i io. —Two Single-phase Transformers Connected on 

Two-phase Primary Lines, Four-wire Secondary. 

% 


The second method is shown in Figure in. This 
method is more universally used when the low volt¬ 
age side supplies motors. It requires a smaller 
amount of copper and one less wire to install. This 
is known as the two-phase three-wire connection. 

In Figure in the individual transformations are 
equal, but owing to the solid connection between 
them at A we have an odd voltage between wires 



















AND SWITCHBOARDS 265 

numbered 1 and 3. This is because the two voltages 
have been interconnected and are equal to 

E x VV 

If E = 220 volts the voltage between wires num¬ 
ber 1 and 3 = 220 X V2 or 220 X 1.41 = 310 volts. 


One Phase 


High Voliage 



One Phase 





•SULQ.QJL 


SMSLSLs 








One Phase % 

A 



One Phase \ 



Fig. hi. —Two Single-phase Transformers Connected to 
Two-phase Primary Lines. Three-wire Secondary. 

The amount of current that will flow over wire 
number 2 is as follows: 

i x \ZT" 

I = The amount of current flowing over either 

wire number one or three. 

The transformer connections to three-phase lines 
are more numerous and exacting and require more 
•care because it is possible, by making wrong con¬ 
nections, to cause serious trouble or damage. 

Possibly the simplest of three-phase connections 





















266 ELECTRIC-WIRING, DIAGRAMS 


is the one known as V or open delta. This con¬ 
nection is shown in Fig. 112. 


3 Phase High Voltage 















OtiOtfO ' 











Low Volfage 3 Phase 


* 

Fig. i 12 .—Open Delta or V, Three-phase. 


In Figure 113 the star-star connection is dia¬ 
grammed. This is known sometimes as the Y Y 
connection. 


3 Phase High Volfage 










SiUJUL 

imm 

jimm) 

winnr| 

MjJ 







Lon Volfage 3 Phase 



Fig. 113. Star-star Three-phase Connection. 


It is possible to use this connection for power 
and light by connecting a fourth wire at the center 
of the star, as shown in Fig. 114. This wire is com¬ 
monly called a neutral. 








































AND SWITCHBOARDS 


267 


In this connection, assuming that the voltage be¬ 
tween lines equals 220 volts, the voltage between 


3 Phase High Vo If age 












JLSJUU 

jcuuJ 

UL9JUU 


Neutral 

nmnr| 

onmr 

nnnnr 











Low Voltage 3 Phase 



Fig. i 14. —Star-star Three-phase with Neutral. 


the neutral wire and either of lines numbers 1, 2, 
or 3 would equal: 


220 
V 3 


220 

i-73 


= 127 Volts 


This voltage is applied to the lamps and the voltage 
between lines I, 2 and 3 applied to motors. 

Probably the most widely used connection is the 
delta-delta connection. 



























268 ELECTRIC-WIRING, DIAGRAMS 


With this connection, in the event of a transformer 
breaking down, it can be removed from service and 
the two remaining transformers operated in open 
delta. With open delta connection, however, only 
66 per cent, of the delta connection is available. 
Fig. 115 shows a delta-delta connection. 


3 Phase High Volfage 













smmi 


MmSL 




wmr 


TOW 


'TOTO 

A 







« 



3 Phase Low Volfage » 



Fig. 115. — Delta-delta Three-phase Connection. 

The low voltage connections of a delta-delta con¬ 
nection should be left open at one point, as at A, 
Fig. 1 1 5 » an< J the voltage impressed on the high 
voltage coils. A voltmeter should then be used to 
test across the connection left open. If the rest of 
the connections have been properly made the volt¬ 
meter pointer will remain at zero. If the connec¬ 
tions are improper the voltmeter will indicate double 





























AND SWITCHBOARDS 


269 


the voltage that exists between B, C and D. This 
indicates that one of the transformers has been con¬ 
nected wrong and must be reversed. This can be 
done by transposing the wires from the transformer 
-where they connect to B, C and D. The test should 
be made until the voltmeter does not indicate, when 
the connection can be made permanent. Care 
should be taken to see that the voltmeter is work¬ 
ing properly. 


t- I 5 *Phase 

Y 





?• 2 n - d Phase 

Y 





ME 


mm 



Insulate 
'Bare Part 


WMF 











d r - d Phase 


Fig. i 16.—T or Scott Connection, Two- to Three-phase 

Transformation. 


The T or Scott connection is used for two-phase 
to three-phase while also transforming voltage. This 
is often necessary where a central station supplies 
two-phase current and the customer has three- 
phase apparatus. The T or Scott connection is 
shown in Fig. 116. 






















270 


ELECTRIC-WIRING, DIAGRAMS 


It is also used by central stations having two- 
phase generating apparatus to transform the three- 
phase for transmission purposes. 

There is very often used a star to delta connec¬ 
tion. When transformers are manufactured they 
are constructed with desired ratios of transforma¬ 
tion. However, in actual practice transformers are 
often connected together to obtain a higher voltage 
than what the transformers individually were wound 1 
for. This can be done on three-phase alternating 
current lines by connecting the high voltage side 
of three single-phase transformers in delta and the 
low voltage coils in star or Y. Fig. 117 shows three 
transformers connected thusly. 


High Voltage 3 Phase 











imm 


imm 


juuism 

Delta A 





75mm 


oocroooo 

Star Y 

9 










■ 


Fig. i 17. —Delta to Star Connection, Three-phase. 

In this connection, assuming that the low voltage 
winding was made for 220 volts, we would obtain: 

220 X \/ 3 = 380 Volts 

Connecting the high voltage coils in star and the 
low voltage coils in delta, as shown in Fig. 118, we 
obtain the following result: 

Assuming that the high voltage coils are wound 

























AND SWITCHBOARDS 


271 


for 2,200 volts and the low voltage coils for 220 
volts, there would be impressed on the high voltage 
coils of each transformer 


= = I2yo v 0 i ts 

Vs 173 

and the ratio of transformation being 2,200:220 or 
10:1 there would be available at the low voltage 

coils a pressure of or 127 volts. 

The standard commercial transformers are so con¬ 
structed that two voltages can be applied at the 
high voltage windings and two voltages obtained 
from the low voltage coils, as shown in Fig. 118. 


< . 2200 ..> 

-<-— . . -//<%> > < . .H00 .> 

<-- — //0 — - - -no 

< -Z20\ . > 


Fig. 118.—Multi Voltage Taps. 


Fig. 118 shows that the coils are tapped in the 
middle, but as a matter of fact four wires are 
brought out on each side of the transformer, as in 


Fig. 119. 


1 

< 

2 : 


i 


pm~T| 


Ujjuu 

fifrri 


1 

? _ < 

^ * 

./ 1 

i 


Transformer Case 


F IG . i 19.—Typical Transformer Winding Diagram. 



























272 


ELECTRIC-WIRING, DIAGRAMS 


By connecting 2 and 3 the coils are placed in 
series. If the ratio of transformation is 20:1 and two 
thousand volts are applied to 1 and 4, there are 
available at 5 and 6, and 7 and 8, one hundred volts, 
and by connecting 6 and 7 two hundred volts will 
be available between 5 and 8. This is the connec¬ 
tion commonly used for three-wire single-phase 
lighting service. By joining 1 and 3, and 2 and 4, 
and applying 2,200 volts at the connections there 
will be 200 volts available between 5 and 6, and 7 
and 8, and 400 volts, by joining 6 to 7, will be avail¬ 
able between 5 and 8. 

All transformers must have, if they are to oper¬ 
ate efficiently, a cooling medium. Some are cooled 
by air which is blown or forced by pressure through 
and around the coils. A compressor capable of giv¬ 
ing a large volume of air at a pressure of about 
two pounds and having its source of supply from 
outdoors, is connected at its outlet to a duct which 
leads to the base of the transformer to be cooled. 
The air flows through the duct to the transformer 
casing and forces the warm or hot air, caused by 
the heating of the windings, out through the top, as 
shown in Fig. 120, which shows the method in a 
general way. 

Oil-cooled transformers are so constructed that 
the coils are immersed in oils, the insulating quali¬ 
ties of which are very high. The oil penetrates to 
all parts of the windings. The case containing the 
oil is generally made having a vertically corrugated 
or wavy construction. This method of construction 


AND SWITCHBOARDS 


273 


presents a large area of surface to the surrounding 
air and is very valuable because the oil thus has a 
large cooling surface through which it dissipates 
the heat generated by the current acting on the 
transformer coils. 



Fig. 120.—Air Cooled Transformer Showing Method of Sup¬ 
plying Air Currents. 

Water cooled transformers have a number of turns 
of pipe within the transformer case and surrounding 
the windings. The oil is cooled by the circulating 
of water through the pipe. The greater the flow of 
water and the lower its temperature the cooler the 
oil will be kept at a given load. 

The temperature rise in a transformer determines 
its ultimate capacity, and the greater the cooling 
medium the greater load it will carry at a given 
temperature. 

In operating transformers it is very essential that 
the temperature of the transformers be carefully 
noted. The temperature rise as indicated by the 
manufacturer should never be exceeded. 

18 













274 


ELECTRIC-WIRING, DIAGRAMS 


CHAPTER XVII 

ELECTRIC METERS.-METER CONNECTIONS DIAGRAMMED, 

AMONG WHICH ARE THE VOLTMETER (a. C. AND 
D. C.), AMMETER (a. C. AND D. C.), D. C. WATT¬ 
METER.-SINGLE-PHASE, TWO-PHASE AND THREE- 

PHASE WATTMETER, CURRENT TRANSFORMERS, 

POTENTIAL TRANSFORMERS. -INCREASING THE 

CAPACITY OF A. C. AND D. C. VOLTMETER USINd 
RESISTANCE AND TRANSFORMER. 

In the distribution of electrical energy, portable 
and stationary electrical instruments are an abso¬ 
lute necessity if the true operating conditions are 
to be known. 

Of all electrical instruments the voltmeter is un¬ 
doubtedly the one most widely used. It is used to 
determine the pressure or difference of potential 
(voltage) between two separate conductors or two 
different points on the same conductor. Voltmeters 
can be obtained, from the manufacturers, having 
scales calibrated to read or indicate any voltage. 
The standard voltmeters are calibrated for 150 or 
300 volts. 

It is possible, however, to read higher voltages 
with these instruments if the following is observed: 
In the case of a direct current voltmeter, which is 
-generally a standard instrument connected in series 
with a known resistance, furnished with the instru- 


AND SWITCHBOARDS 


275 


ment, it is necessary only to connect additional 
resistance in series with the voltmeter. 

If it is desired to test for a higher voltage than 
that for which the scale is calibrated, a resistance 
equal to the voltmeter resistance will double the 
range and the scale indication must be multiplied 
by two. Fig. 121 shows a voltmeter and additional 
resistance thus connected. 


lo Line 



Fig. 121. —Increasing Capacity of Voltmeter. Scale Reading 

Multipliable by Three. 


By inserting additional like resistances and multi¬ 
plying the scale reading or indication by the num¬ 
ber of resistance units used any voltage can be de¬ 
termined. This is termed multiplying the voltage. 
Various instruments used for this same purpose 
and known as “multipliers can be obtained from 
the manufacturers of the various voltmeteis. An 
approximate idea of the voltage to be measured 
should be known, as it is possible that too few re¬ 
sistance units might be used and the voltmeter sub- 
























276 ELECTRIC-WIRING, DIAGRAMS 


jected to a greater voltage than that for which it 
was intended, in which case the voltmeter would be 
•damaged. 

An alternating current voltmeter can be used on 
most any alternating voltage beyond its calibrated 
•capacity provided that a potential transformer, the 
low voltage winding of which does not exceed the 
rated voltage of the voltmeter, be connected to it. 
In this way the scale of voltmeter w r ould indicate in 
exact proportion to the ratio of transformation cf 
the potential transformer. Thus, if the transformer 
ratio was 20 to 1 the scale indication of the volt¬ 
meter would be multipliable by 20. 



Fig. 122.— Voltmeter and Instrument Transformer. 

Fig. 122 is a diagram of a voltmeter and potential 
transformer connected as described. 

Of course, it would not be necessary to use a 
transformer where voltages not exceeding the%cale 
•of the voltmeter are to be determined. 











AND SWITCHBOARDS 


277 


The ampere-meter, or ammeter, measures and in¬ 
dicates instantly the quantity of current passing 
over a conductor. Its use is absolutely necessary 
because the various motors, generators, transform¬ 
ers, wires, cables, switches and, in fact, all electrical 
apparatus have a limited current-carrying capacity 
and without ammeters it would be possible to un¬ 
knowingly overload them and probably with harm¬ 
ful results. 

Direct current ammeters are made without shunts 
up to two-hundred-ampere capacity. With shunts 
the ampere capacity can be raised to very large 
amounts. Ammeter shunts are made of alloy hav¬ 
ing a slightly higher resistance than the copper 
conductor. The current, in passing through this 
shunt, causes a slight fall of potential, due to the 
higher resistance, across the shunt. This drop of 
voltage or potential increases as the current flowing 



Fig. 123—D. C. Ammeter and Shunt Showing Current Flow. 












278 ELECTRIC-WIRING, DIAGRAMS 


through the shunt increases. The ammeter, which 
when used with a shunt is a millivolt meter, is con¬ 
nected to the shunt, is excited by the voltage that 
is resisted by the shunt in direct proportion and is 
indicated on the scale of the ammeter as amperes 
instead of millivolts. (A millivolt equals one one- 
hundredth part of a volt.) 


Ammeter. 



Ammeter and Shunt. 

Fig. 123 is a diagram of an ammeter connected 
and used with a shunt. Arrows show the direction 
of the flow of current. 

















AND SWITCHBOARDS 


279 


Alternating current ammeters are similar to the 
direct current ones and are used and connected in 
a like manner except that, in place of a shunt, a 
current transformer is used. 



Fig. 124.—Current Transformer. 

A current transformer is shown in Fig. 124 and 
is diagrammed in Fig. 125 with ammeter connected. 

A current transformer consists mainly of an iron 
core having a turn or two of the current-carrying 



Fig. 125.—Current Transformer and Ammeter. 

conductor and a finer winding of a large number 
of turns. There is no metallic connection between 
these separate coils. When the current flows 
through the main conductor there is generated in 















28o ELECTRIC-WIRING, DIAGRAMS 


the finer windings a voltage the strength of which 
is governed by the amount of current flowing 
through the main conductor. This voltage acts on 
the elements of the ammeter and causes a pro¬ 
portionate scale deflection. Under certain condi¬ 
tions this voltage can become dangerously high. 
Should the transformer finer windings, known 
as the secondary, be open-circuited with a heavy 
current flowing in the primary or main conductor, 
the secondary voltage could arise to such a dan¬ 
gerous height that the transformer insulation might 
be punctured and the transformer rendered useless. 
If it is necessary at any time to install a current 
transformer before the instrument is at hand, the 
secondary should be short-circuited and made to 
remain that way until the instrument is ready to 
be connected. 

There will be noticed in the diagram, Fig. 124, 
several arrows. While there is no positive or uni¬ 
directional flow of current in alternating current 
there are in a transformer points where the in¬ 
stantaneous flow of current is in certain directions 
and the arrows in this case indicate where the flow 
is simultaneous. 

The wattmeter is a combination of a voltmeter 
and ammeter with the active elements of each on 
one shaft to give an indication of or to record the 
number of watts passing over the wire to which it 
is connected. 

There are several kinds of wattmeters. Possibly 
the best known is the recording kilowatt meter used 


AND SWITCHBOARDS 


281 


by the electric light company. This type of meter 
makes a record of the number of watts or kilowatts 
consumed and records a total by means of the dials 
on its face. 

Then the indicating wattmeter used mostly on 
switchboards. On this type there is a pointer which 
moves up and down the scale as the power or elec¬ 
trical energy consumed on the line becomes greater 
or smaller. 

Then the curve-drawing wattmeter, which is used 
on power circuits to show the character of the load. 
This instrument, the hand of which holds a pen 
containing ink, moves across a tape which is grad¬ 
uated into divisions, each representing so many 
watts or kilowatts. The hand is connected mechan¬ 
ically to the moving elements, which in turn are 
acted upon by the current passing through the 
wires, and moves forward and backward as the elec¬ 
trical energy is consumed, thus drawing a curve 
which is an exact reproduction of the current con- 



Fig. 126.—Diagram of Connections of Two-wire Direct 

Current Wattmeter. 













282 ELECTRIC-WIRING, DIAGRAMS 


sumed at each minute of the time it is operating. 
The tape is attached to a clock movement which 
carries the tape forward at a certain speed. The tape 
is also graduated into time divisions horizontally. 

The simplest one to connect is the two-wire direct 
current wattmeter which is diagrammed in Fig. 126. 

In the actual instrument the current coil termi¬ 
nals are easily distinguished from the pressure or 
voltage coils because of their heavier construction. 
If, when connected, the instrument operates re¬ 
versed, changing the pressure or voltage wires will 
cause it to operate in the proper direction. 

The three-wire direct-current wattmeter is con¬ 
nected as shown in Fig. 127. 


Sour 

ce L 

Senes Coils 

■ 

Potential 

Coils 



-' U UvJUUUUU 0] 

Senes Coil | 



Loa 

d' 1 


Fig. 127. —Diagram of Connections of Three-wire Direct 

Current Wattmeter. 


The single-phase wattmeter is similar to the two- 
wire direct-current wattmeter, except that in ca¬ 
pacity over two-hundred-amperes-current trans¬ 
formers are used. Above certain voltage potential 
transformers are used to reduce the line voltage 
to a lower value, so as to be appliable to the in- 















AND SWITCHBOARDS 


283 


strument. Fig’. 128 shows a single-phase wattmeter 
with current and potential transformers dia¬ 
grammed. 


Source 



. Potential Transformer 

-. 

g Potential 

" Coils \ 

mmmmmsu 


Load 



Current Transformer 


Fig. 128. —Diagram of Connections of Two-wire Single¬ 
phase Wattmeter. 


Fig. 129 is a diagram of the three-wire single¬ 
phase wattmeter. 



Fig. 129. —Single-phase Three-wire Wattmeter Connections. 

Single-phase and two-phase wattmeters will op¬ 
erate in a forward direction if the connections are 
properly made. If it operates otherwise it is only 
necessary to reverse the various pressure or voltage 
connections. In the two-phase wattmeter it is best 






























284 ELECTRIC-WIRING, DIAGRAMS 


to test for correct operation on each phase sepa¬ 
rately, as each phase should indicate forward. This 
can be very easily done with the load on by dis¬ 
connecting one of the pressure wires of the opposite 
phase to be tested. Never disconnect the current 
wires after the load is being carried. 

Three-phase wattmeters should be tested by con¬ 
necting one phase at a time. If the power factor 
of the circuit is below 50 per cent., one element of 
the meter will indicate minus or backward. This 
will be correct. The other element of the meter 
will indicate positive or forward. 

If it is known that the power factor is above 50 
per cent, and one phase records minus, the pressure 
wires should be interchanged. 


Source 









1 | 
s > 1 





Poteni, 

a! J~ra 

nsformers 




§ * g 

9 9 

2 5 

0 0 



r f 





..Current Waffmei 

1/ Transformers 

f er--' r 

22m 

(00085 


G5OT 



















Load 


Fig. 130. —Two- and Three-phase Wattmeter Connections. 

In any event, except under perfect conditions, 
which never exist in practice, such as balanced 
phases and unity power factor, one element of the 














































AND SWITCHBOARDS 


285 


meter will read lower than the other. This is the 
element that will read minus on less than 50 per 
cent, power factor. 

A very simple test to determine whether the true 
connections have been made is to apply a non- 
inductive load, such as incandescent lamps. Lamps 
being 1 of a resistive nature, only have a power fac¬ 
tor of unity, or 100 per cent. In this case both ele¬ 
ments of the meter should read positive or forward. 
If not, the pressure wires should be transposed on 
the one reading minus or backward. 

Fig. 130 is a diagram of the connection of either 
two- or three-phase three-wire wattmeter, showing 
current and potential transformers. 


286 ELECTRIC-WIRING, DIAGRAMS 


CHAPTER XVIII 

ALTERNATING CURRENT MOTORS.-MULTI-SPEED INDUC¬ 
TION MOTOR.-ADJUSTABLE SPEED INDUCTION 

MOTOR.-WIRING CONNECTIONS FOR INDUCTION 

MOTOR.—CONNECTIONS FOR THREE-PHASE MOTOR. 

-TIME LIMIT RELAYS.—INTERNAL WIRING OF 

COMPENSATOR. 

The rapidly increasing use of electrical energy in 
the driving of machine tools, elevators, cranes, pumps 
and manufacturing equipment of all kinds through the 
electric motor as a medium makes a knowledge of 
their connections particularly valuable. 

The alternating current motor is coming into greater 
use daily because of the ever-increasing distribution 
of alternating current through long transmission lines 
upon which are impressed high voltages. The in¬ 
duction motor, because of its ruggedness and ability 
to withstand severe service, is becoming more and 
more popular among users of electrical driven ma¬ 
chinery. The lack of moving electrical contacts, such 
as commutators, makes its use desirable in places 
manufacturing easily ignitible material, as in a powder 
mill, textile mill and where gasoline and other ex¬ 
plosive vapors prevail. Due to their being no com¬ 
mutator and brushes there can be no arcing as in a 
direct or continuous current motor. Due to there 
being no exposed moving parts to rapidly wear, the 
induction motor is particularly adaptable for use in 


AND SWITCHBOARDS 287 

cement mills and other places where gritty particles 
are partially suspended in the surrounding air. 

Induction motors are fundamentally of a constant 
speed nature and require a special construction to 
make of them an adjustable speed machine. This 
fact makes them particularly adaptable to line shaft 
drives to which are connected, mechanically, through 
belts, many machines. On lathes and other machine 
tools with change speed gears they find, because of 
their small size and weight compared with their horse¬ 
power output, a ready field of usefulness. On machine 
tools requiring but one speed they are well suited 
for driving them. Many manufacturers are now 
supplying machines with motors mounted thereon if 
desired. 


MULTI-SPEED INDUCTION MOTOR. 

There has been developed and placed on the market 
a multi-speed induction motor that has found a par¬ 
ticularly useful field in the driving of lathes and other 
tools requiring a multiplicity of speeds. Due to its 
large bulk and weight compared to its horsepower, 
its application is somewhat limited. Its size is due to 
the large amount of magnetic metal and the windings 
within it. The changes in speed are made by chang¬ 
ing the number of poles connected to the source of 
electrical supply. The speed of an induction motor is 
controlled by the alternations of the circuit and the 
number of poles connected in the motor as shown in 
the following: 


288 ELECTRIC-WIRING, DIAGRAMS 


Alternations 

Poles 


= Motor speed. 


Thus a four-pole induction motor connected to a 
6o-cycle circuit would have a speed of 1800 R.P.M. 


60 cycles = 


7200 Alternations 
4 Poles 


1800 R. P. M. 


On a 25-cycle circuit the speed of a four-pole 
motor would be 725 R.P.M. 


2S_X6oX_ 2 _ 3000 _ R p M 
4 4 


The number of poles generally employed in a multi¬ 
speed motor are 2-4-8-12. When connected to a 
circuit of sixty cycles or seventy-two hundred alterna¬ 
tions per minute a motor of this construction will give 
respectively 3600-1800-900 and 600 revolutions per 
minute. When connected mechanically to a machine 
having seven changes of speed in the gearing, with 
the four speeds of the motor, twenty-eight different 
speeds are available. 


ADJUSTABLE SPEED INDUCTION MOTOR. 

An induction motor with adjustable speed char¬ 
acteristics is met with in the wound rotor type. This 
type is used where large starting torque at slow speeds 
is required as in the hoisting of some weight as in 
the raising of an elevator, the raising of a load by 
a crane and other hoisting of a like nature. The leads 
from the windings of a wound rotor are connected 







AND SWITCHBOARDS 


289 


to three metal wheels secured to and insulated from 
the rotor shaft. These wheels are termed slip rings. 
On each of these rings a brush, usually made of 
carbon, rests under spring pressure to secure good 



Fig. 131. —Diagram of Connection of Three-phase Slip Ring 

Motor with Controller. 

electrical contact. Wires from these rings are car¬ 
ried to a controller. The controller, operated manu¬ 
ally, changes the connections from a resistance to the 
leads to the slip rings. As the resistance is lessened 
the motor gains in speed. When all the resistance 

























































































290 ELECTRIC-WIRING, DIAGRAMS 


is removed from the circuit the rotor winding is short 
circuited and the motor becomes to all intents and 
purposes a plain induction motor and operates as 
such. As the resistance is introduced into the rotor 
circuit the motor speed lessens. 

Fig. 131 is a diagram showing the connections of an 
induction motor of the wound rotor type. 

WIRING CONNECTIONS FOR INDUCTION MOTOR. 

The wiring connections for an induction motor of 
five horsepower or less are very simple. It is the 
custom to connect the motor directly to the line by 
means of a switch. <In the event of the motor being 
two-phase a four-pole switch would be required unless 
the two-phase system consisted of three wires instead 
of four. A diagram for a two-phase motor con¬ 
nected to a two-phase four-wire system is shown in 
Fig. 132. 

A double throw switch is required because the start¬ 
ing fuses must be of a size large enough to withstand 
three times the normal full load running current re¬ 
quired by the motor. These fuses will not protect 
the motor while running. Consequently, a means 
must be provided of connecting the motor to fuses 
that will protect and the use of the double throw 
•switch is the simplest way. The operation is to throw 
the switch onto the side with the running fuses first 
and when the motor has attained full speed to throw 
the switch blades onto the side with the running fuses. 
To prevent the switch from remaining in the starting 


AND SWITCHBOARDS 


291 


position a spring is so arranged as to push the blades 
out of contact or to automatically throw the switch 
blades into the running position. 

CONNECTIONS FOR THREE-PHASE MOTOR. 


For a three-phase motor of like horsepower the 
switch and connections are the same except that a 
three-pole switch is used. This is true also of a 



of a 2-phase Motor, 5 Horsepower 
and lees to a 2- n hase 4-wire System. 





























































292 


ELECTRIC-WIRING, DIAGRAMS 


motor connected to a two-phase three-wire system. 
In this case the fuse on the wire that connects the 
two phases of the system must be of a current 
carrying capacity equal to i XV 2 * 1 his is because 
it is called upon to carry current to both phase wind¬ 
ings of the motor. While the currents supplied to 
the separate motor windings are the same, they occur 
at such a time that the angular displacement is equal 
to i X VT. 



Fig. 133.— Diagram of Connection of Two-phase Motors 
Above Five Horsepower to a Four-wire System. 

Two- and three-phase induction motors of seven 
and one-half horsepower are started by means of an 
auto-transformer or compensator. For two-phase cur¬ 
rent the transformer is equipped with two windings 







































































AND SWITCHBOARDS 


293 


and for three-phase it has three windings. The ob¬ 
ject of the compensator is to reduce the starting 
current to a minimum. Fig. 133 is a diagram of the 


From Switch 



connections of a two-phase compensator to an in¬ 
duction motor. 

TIME LIMIT RELAYS. 

An improvement over the fuse block is to install 
in its place inverse time limit relays. The relays, 
there will be two, one on each phase, are connected 

































?94 ELECTRIC-WIRING, DIAGRAMS 


in series with the coils of the motor as shown in Fig. 
134 and are actuated by the current traversing through 
several windings of wire surrounding an iron core 
free to move. The iron core, when a sufficiently 
strong magnetic field has been created, is drawn up¬ 
wards opening a pair of contacts which in turn opens 



Fig. 135.—Diagram of Connection of a Three-phase Motor 

and Compensator. 

the circuit to a solenoid, de-energizing it. The 
solenoid being thus deprived of its magnetism allows a 
core or plunger to drop, releasing a catch which per¬ 
mits the oil switch of the compensator to return to 
the off position. When the voltage of the circuit 
fails the solenoid acts in a like manner. This is to 
prevent the motor starting without warning when the 
power returns. The core of the relay is retarded 
in its upward travel by a dash pot at its base. This 
provides the time limit feature and prevents the relay 



















































AND SWITCHBOARDS 


295 


from opening the circuit under any other than danger¬ 
ous overload conditions. Fig. 134 is a diagram of a 
relay of this type and its connections. The connec¬ 
tions for a three-phase compensator are shown in 

Fig- 135- 


INTERNAL WIRING OF COMPENSATOR. 


The internal connections of the compensator are 
changed from the starting position by means of a 




Fig. 136. —Diagram of Internal Connection of a Three- 

phase Compensator. 


double throw oil switch. Fig. 136 is a diagram of 
the internal connections. The handle is first thiown 
to the starting position by a strong quick movement 
and held there until the motor has attained full speed. 























296 ELECTRIC-WIRING, DIAGRAMS 


This will be recognized by the motor attaining a steady 
whistling noise after making a rising, whistling sound 
while attaining speed. The handle of the compensator 
should then be thrown to the running position by a 
strong quick movement. 

When installing the wiring for a motor requiring 
a compensator the switch and fuse block containing 
the running fuses, or the relays, of the motor should 



Fig. 137.— Showing Assembly of Parts in the Wiring for 
A. C. Motors above Five Horsepower. 

be mounted in one sheet metal box. The sheet metal 
box and compensator should be mounted on an angle 
iron stand as shown in Fig. 137, which also shows 
the motor connected. With this construction the com¬ 
pensator, angle iron frame and motor, are all con¬ 
nected to ground when the motor is grounded. This 































AND SWITCHBOARDS 


2 97 

prevents a person from getting a shock in the event 
of an accidental ground happening in the compensator, 
switch box, wiring or motor. 

In power wiring it is good practice to enclose all 
wiring and switches with a metallic casing. It serves 
two good purposes, one, the protection of the wires 
and switches from mechanical injury, another, the 
protection of the individual from shock due to coming 
into accidental contact with exposed live parts. 

























■ V 

































Consult Supplementary Index on page 315. 


INDEX 


A 

Absorption of light by globes, 164. 

A. C. ammeter and current trans¬ 
former, 279. 

Accessories of conduit, 138. 

Adjustment of arresters, 207. 

Alternating current, effect of ca¬ 
pacity on an, 231. 

Alternating current, effect of in¬ 
ductance, 230. 

Alternating current, effect of re¬ 
sistance, 230. 

Alternating current, line losses, 
224, 

Alternating current mains, size 
of wire for, 242. 

Alternating current waves, 229. 

Alternator connections for three- 
phase, 257. 

Alternator connections for two- 
phase, 257. 

Alternator elements, 122. 

Ammeter, direct current, 277. 

Ammeter, multi-volt meter, 278. 

Ammeter, shunt, 277. 

Amperes—allowed in conduit 
work, 148. 

Amperes allowed in insulator 
work, 148. 


Amperes with a given insulation 
resistance, 149. 

Analysis of a ten-lamp circuit, 43. 

Analysis of a 2 20-volt system, 
103. 

Analysis of drop in ten-lamp cir¬ 
cuit, 45. 

Analysis of switchboards, 199. 

Analysis of Wiedemann system, 
47, 48. 

Angle of lag, 239. 

Apparatus of lighting circuits, 
176. 

Apparatus of switchboards, 168. 

Application of rotaries, 220. 

Application of shunt and com¬ 
pound wound dynamos, 84. 

Application of Wheatstone 
bridge, 91. 

Arc light system, 28. 

Area lit and candle power, 463. 

Arresters, lightning, 201. 

Arresters, mounted, 201. 

Armored conduit in damp places, 
136. 

Assembling a panel switchboard, 
196. 

Asphaltic paper conduit, 128. 

An alternating current meeting 
inductance, 226. 


239 



3°° 


INDEX 


Auto transformers, 249. 
Automatic dynamo, 171. 
Auxiliary field, 256. 

Average power factors 248. 

B 

Back EMF. of motor, 115. 

Back pressure of inductance, 226. 
Balancing the bridge, 92. 
Balancing a three-wire system, 
104. 

Bends of conduit, 128. 

Bends, couplings, elbow clamps, 
133- 

Branches, feeders, mains, 66. 
Brass armored, accessories of, 

138- 

Brass armored conduit, 128. 
Bridge of lamps, 92. 

C 

Cables, 217. 

Calculation of back EMF., 118. 
Calculation of capacity reac¬ 
tance, 234. 

Calculation of drop, 24. 
Calculation of impedance, 235. 
Calculation of mains, feeders, 
branches, 68. 

Calculation of power, 38. 
Calculation of resistance of wires, 
25- 

Calculation of reactance, 233. 
Calculation of a simple circuit,42. 
Calculation of two-phase mains, 
244. 


Calculation of weight of wire,i 10. 

Calculation of wires for three- 
wire system, 106. 

Calculating unequal resistances 
in multiple, 35. 

Calculating a power line, 59. 

Candle power of commercial 
lamps, 160. 

Candle power and pressure, 161. 

Candle power per watt, 159. 

Capacity of generator panels, 
194- 

Capacity and inductance, 232. 

Capacity in a line, 224. 

Capacity reactance calculated, 
234- 

Carrying capacity of wires, 40. 

Center of distribution, 72. 

Centers of distribution, table of, 
74- 

Central station lighting, 85. 

Chandeliers, use of, 166. 

Character of glass and light, 164. 

Choosing conduit, 130. 

Choosing globes, 164. 

Circuit breaker, 170. 

Circuit breakers in power plants, 
187. 

Circuit of ten lamps, analyzed, 
43- 

Circuits tested, 209. 

Circuits, with average power 
factors, 248. 

Circular mils and drop, 31. 

Circular mils, drop and sizes, 
table of, 71. 


INDEX 


Circular mils and size, by wiring 
table, 53. 

Circular mils, feet of wire and 
ohms, table of, 33. 

Circular mils for two-phase, 244. 

Circular mils for three-phase, 247. 

Circular mils for single-phase, 
243- 

Classification of grounds, 212. 

Cleats, knobs, moulding, 126. 

Coal consumption, 162. 

Coal and lamp wear, 162. 

Combination fixture work, 150. 

Combination of two- and three- 
wire circuits, 107. 

Combination of two- and three- 
wire system, 109. 

Commercial and electrical effi¬ 
ciency, 118. 

Comparison of inductance and 
reactance, 236. 

Comparison of size of wire with 
two- and three-wire system, 
105. 

Comparative table of drop cir¬ 
cular mils and sizes, 71. 

Comparative table of regular and 
calculated sizes, 53. 

Complete cycle, 238. 

Complete panel switchboard,203. 

Compound generators, speed of, 
182. 

Compound wound dynamos, 84. 

Compound wound generator con¬ 
nections, 171. 

Concealed work, 147. 


301 

Conditions of switchboard de¬ 
sign, 189. 

Conduit concealed and exposed, 
127. 

Conduit in new buildings, 127. 

Conduit in old buildings, 127. 

Conduit, kinds of, 128. 

Conduits or tubes defined, 140. 

Conduit requirements, 141. 

Conduit system, laying out of a, 
144- 

Copper cross section, 261. 

Copper deposited by one cou¬ 
lomb, 19. 

Copper required for alternating 
current wires, 249. 

Copper saved, 62. 

Cost and percentage of drop, 65. 

Cost of installation and material, 
64. 

Cost of light and life of lamp, 86. 

Cost of lost light, 161. 

Cosine of angle, value of, 240. 

Cosines, table of, 241. 

Couplings for joining conduit, 
136. 

Covering of wires and cables, 217. 

Cross section and resistance of 
wires, 25, 61. 

Cross-section of copper, 261. 

Current in branch circuits, 88. 

Current distribution in wires, 44. 

Current in each part of the cir¬ 
cuit, 43. 

Current in the wire, 43. 

Current, lag of, 228. 


3° 2 


INDEX 


Current, a wattless, 239. 

Current ratio, 260. 

Current transformers, instanta¬ 
neous flow of current, 279. 

Current transformer and A. C. 
ammeter, 279. 

Current transformer, voltage 
danger, 280. 

Curve-drawing wattmeter, 281. 

Cycle, zero points of, 227. 

D 

Damp basements, 215. 

Day’s light and coal, 162. 

Degradation of electrical energy, 
225. 

Degrees of a cycle, 238. 

Definition of angle of lag, 239. 

Definition of the ampere, 18. 

Definition of the mil, 25. 

Definition of a period, 122. 

Definition of tubes or conduits, 
140. 

Definition of wiring, 15. 

Delta connection three-phase, 268. 

Delta-delta testing for accuracy 
of connections, 268. 

Delta-delta three-phase connec¬ 
tion, 268. 

Delta-stem three-phase connec¬ 
tion, 270. 

Detecting breaks in line, 215. 

Determination of two-phase cir¬ 
cuits, 258. 

Development of wiring table, 51. 


Diagram of connections, two- 
wire, single-phase wattmeter, 

283. 

Diagram of connections, three- 
wire, single-phase wattmeter, 
283. 

Diagram of connections of two- 
wire, D. C. wattmeter, 281. 

Diagram of connections of three- 
wire, D. C. wattmeter, 282. 

Diagram of current transformer 
and A. C. ammeter, 279. 

Diagram of D. C. ammeter and 
shunt, 277. 

Diagram of Delta-delta connec¬ 
tion, 268. 

Diagram of Delta-delta, three- 
phase transformer connections, 

268. „ 

Diagram of Delta star connec¬ 
tions, 270. 

Diagram of four centers of dis¬ 
tribution, 80. 

Diagram of limited drop, 78. 

Diagram of potential trans¬ 
former and voltmeter, 276. 

Diagram, primary and secondary 
transformer connections, 262. 

Diagram of star-star connection, 
266. 

Diagram of star-star, three- 
phase with neutral, 267. 

Diagram of Scott connection, 

269. 

Diagram of single-phase trans¬ 
former, 259, 260. 


INDEX 


303 


Diagram of single-phase trans¬ 
former in multiple, 262. 

Diagram of shunt generators in 
multiple, 173. 

Diagram of three-wire system, 
balanced, 107. 

Diagram of two- and three-phase 
wattmeter, showing potential 
and current transformers, 285. 

Diagram two-phase,‘ four-wire' 
secondary, 264. 

Diagram two-phase, three-wire 
secondary, 265. 

Diagram of two-phase trans¬ 
former connections, 264. 

Diagram of voltmeter and re¬ 
sistance units for multiplying 
voltmeter readings, 275. 

Diagram of V or open delta con¬ 
nection, 266. 

Diagram of wattless current, 240. 

Differential voltmeters, 195. 

Differentially wound motor, 113. 

Direct current ammeter, 277. 

Direction of current in trans¬ 
formers, 263. 

Distribution of current in wires, 
44- 

Distribution of lamps, 165. 

Distribution of power by ro¬ 
taries, 221, 222. 

Distribution of power, 255. 

Distribution, sub-centers of, 77. 

Distribution sheet, 152. 

Drilling the marble, 190. 

Drop affected by temperature, 41. 


Drop calculated, 24, 26. 

Drop in the armature, 83. 

Drop in brapch arms, 89. 

Drop in buildings, 85. 

Drop and circular mils, 31. 

Drop and size of feeders, mains, 
branches, 68. 

Drop of potential, 23. 

Drop per 1000 feet per ampere, 
60. 

Drop in Wiedemann system, 49. 

Dry goods and department stores, 
166. 

Dynamos for incandescent light¬ 
ing, 79- 

Dynamos, shunt and compound 
wound, 84. 

E 

Effect of back EMF., on wiring, 
115- 

Effect of capacity on an alternat¬ 
ing current, 231. 

Effect of center of distribution on 
drop, 73. 

Effect of frequency, 228. 

Effects of high pressure on light, 
160. 

Effect of inductance on an alter¬ 
nating current, 230. 

Effect of overload, 180. 

Effect of resistance on electricity, 
225. 

Effect of resistance on an alter¬ 
nating current, 230. 


304 


INDEX 


Effect of volts on weight of cop¬ 
per, 102. 

Efficiency of motors, 117. 

Efficiency of motors and circular 
mils, 120. 

Efficiency of motors and weight 
of wire, 121. 

Efficiency of rotary converters, 
221. 

Electric light system, items of, 
37- 

Electric lighting, rotaries em¬ 
ployed for, 254. 

Electrolytic work, switchboards 
for, 197. 

Elements of an alternator, 122. 

Elements of a transmission plant, 
253- 

Elements of a wiring system, 63. 

EMF. formula for dynamos, 79. 

Enameled iron conduit, 129. 

Equal resistances in multiple, 33. 

Equalizer bar, 181. 

Equalizing generators, 183. 

Equalizing the pressure, 74. 

Equipment of streets with three- 
wire system, 103. 

Estimating circular mils and 
gauge number, 58. 

Estimating on conduit work, 153. 

Example of center of distribution, 

/o* 

Examples of drop of potential, 36. 

Exposed and concealed conduit, 
127. 

Exposed-work, 147. 


F 

Factors, power, 246. 

False resistance, 229. 

Features of alternating currents, 

223. 

Feeders, branches, mains, 66. 
Feeder panel, back and front, 
202. 

■Feeder panels, 196. 

Feeder switchboard, illustrated, 
200. 

Feeding system of street railway, 
204. 

Fire underwriters, approval of 
conduit work, 142. 

Flexible cord, steel armored, 
136. 

Flexible metallic conduit, 128. 
Flexible non-metallic conduit, 
128. 

Flexible tubing, 131. 

Floors controlled, 178. 

Formula for calculating EMF. in 
dynamo, 79. 

Formula for calculating size of 
wire, 30. 

Formula for effect of heat on 
wires, 41. 

Formula for induction reactance, 

233- 

Formula for impedance, 235. 
Formula for three-phase wiring, 
247- 

Formula for three-wire system, 
106. 


INDEX 


305 


Forward pressure of inductance, 
226. 

Four-wire secondary two-phase 
transformation, 264. 
Frequency, 123. 

Frequency, effect of, 228. 

Front and back of feeder panel, 
202. 

Fuses, 172. 

Fuse panels, 106. 

G 

General principles of switch¬ 
board construction, 206. 
Generation of EMF., 114. 
Generator panels, 194. 

Generator switchboard, illus¬ 
trated, 199. 

Generators equallized, 183. 
Getting size of wire in electric 
lighting, 57. 

Globes and light, 164. 

Ground detector, 171. 

Ground detector, operation of, 

209. 

Ground detector, principle of, 

210. 

Ground detector for three-wire 
system, 211. 

Grounded circuits, location of, 
214. 

Grounded wires, 150. 

H 

Henry, unit of self induction, 236. 
High tension arc lighting, 28. 


Hooded insulators, 216. 

How ground is detected, 212. 

How the EMF. is varied, 81. 

Hygienic benefits of electric 
lighting, 16. 

I 

Illustration of sub-station distri¬ 
bution, 255. 

Impedance, calculation of, 235. 

Incandescent lamps, 85. 

Incandesent lamps, light of, 
158. 

Incandescent lighting, dynamos 
for, 79. 

Indicating wattmeter, 281. 

Individual mains, 67. 

Inductance and capacity, 232. 

Inductance in an alternating cur¬ 
rent circuit, 226. 

Inductance compared with re- 
sistence, 229. 

Inductance, with entering cur¬ 
rent, 237. 

Inductance and lag, 231. 

Inductance wirh leaving current, 
237- 

Inductance, principle of, 225. 

Induction motor, 249. 

Induction motor parts, 250. 

Induction reactance, 233. 

Installation of conduit, 145. 

Installation and material, cost of 
64. 

Insulation of conductors, 145. 

Insulation of insulators, 216. 


3°6 


INDEX 


Insulation, kinds of, 99. 
Insulation protected, 100. 
Insulation resistance, 94. 
Insulation resistance, limit of, 
149- 

Insulation resistance measured, 
98. 

Insulation resistance of tall build¬ 
ings, 97. 

Insulation resistance of wire, 95. 
Insulating joints, 150. 

Insulating materials for electrical 
work, 146. 

Intermediate sizes of wire calcu¬ 
lated, 56. 

Iron armored conduit, 128. 

Iron armored, accessories of, 138. 
Iron conduit requirements, 143. 
Items of an electric light system, 
37 - 

J 

Joints, soldered, 151. 

Joining conduits by couplings, 
136. 

Junction boxes, 134. 

K 

Kilowatt, meaning of, 39. 

Kinds of conduit, 128. 

Kinds of insulation, 99. 

Kinds of wiring, 125. 

Kirchoff’s la w, 88. 

4 

L 

Lag defined, 230. 

Lag of the current, 228. 


Lag and inductance, 231. 

Lamps, distribution of, 165. 
Lamp efficiency, 160. 

Lamp filaments, 86. 

Lamps in series, drop calculated, 
27- 

Large power stations, 220. 

Lamp rating, 159. 

Laying out a conduit system, 
144- 

Length of wire and drop, 26. 

Life of a lamp, 17. 

Life of lamps and cost of light, 

86 . 

Light and efficiency, 160. 

Light and globes, 164. 

Light effect with shades and 
globes, 164. 

Light obtained from low pres¬ 
sure, 163. 

Light of lamps, 158. 

Light per square foot, 163. 
Lightning arresters, 201. 
Lightning arresters, principle of, 
206. 

Lightning by the three-wire sys¬ 
tem, 101. 

Lighting circuits, apparatus of, 
176. 

Lightning circuit, power factors, 

248. 

Lighting system, two-phase, 255. 
Limited drop diagram, 78. 

Limit of insulation resistance, 
149- 

Line capacity, 224. 


INDEX 


3cr 


Line losses, with alternating cur¬ 
rents, 223. 

Load panels, 195. 

Locating grounded circuits, 214. 
Loss of energy in transformers, 
260. 

Lost light, cost of, 161. 

Lamp pressure, 17. 

M ' 

Magneto, testing with, 213. 
Mains, feeders, branches, 66. 
Marble for switchboards, 147. 
Meaning of a coulomb, 19. 
Meaning of a kilowatt, 39. 
Meaning of L, 237. 

Meaning of self induction, 225. 
Meaning of the volt, 18. 
Measurement of insulation re¬ 
sistance, 98. 

Measurement of volts, 18. 
Measuring resistance of lamp, 
hot, 93. 

Mechanical work of conduit in¬ 
stallation, 145. 

Method of calculating circular 
mils for motors, 119. 

Method of getting all wire sizes, 

50 , Si, 52, 53, 54, 55, 56, 57- 

Mil defined, 25. 

Milli-voltmeter ammeter, 278. 
Motor connections, 113. 

Motor, induction, 249. 

Motor line, calculation of, 59. 
Motors, efficiency of, 117. 


Motors, single-phase, 251. 

Motors, synchronous, 251. 

Motors, types of, 112. 

Mounting apparatus on slate, 
191. 

Mounting of lightning arresters, 
201. 

Movement of wavers, 229. 

Multiple circuits, 33. 

Multiple connections of two- 
shunt machines, 173. 

Multiple wiring, 29. 

Multi-voltages, 272. 

Multi-voltage tops in transform¬ 
ers, 271. 

Multiplying voltmeter reading, 
275- 

N 

Names of switchboard sections, 
193- 

National electrical code, 157. 

Neutral wire, 104, 266-7. 

O 

Ohms, circular mils, and feet of 
wire, 33. 

Ohm’s law, 17. 

One and two centers of distribu¬ 
tion, 75. 

Open delta connections, 266. 

Operation of the ground detector, 
209. 

Outlet and junction boxes, 134. 

Over compounding, 184. 


3 o8 


INDEX 


Over compounding, per cent, of, 
185. 

Overboard effect, 180. 

P 

Panel boards, 154. 

Panel board requirement, 156. 

Panel switchboards, 192. 

Panel switchboards analyzed, 
198. 

Parts of switchboards for D. C. 
generators, 208. 

Per cent, of over compounding, 
185. 

Percentage of drop, 29. 

Percentage of drop and cost, 65. 

Period defined, 122. 

Petticoat insulators, 216. 

Pilot lamp, 171. 

Plain unarmored, accessories of, 
138- 

Plan of lighting and switching, 
152. 

Points about motors, 116. 

Potential, drop of. 23. 

Potential transformer used with 
voltmeter, 276. 

Power calculated, 38. 

Power, distribution of, 255. 

Power factors, 246. 

Power factors for lighting circuit, 
248. 

Power factors, table of, 245. 

Practical connections of a shunt 
motor, 117. 


Pressure and illumination, 161. 

Principle of lighting arresters, 
207. 

Principle of the ground detector, 
210. 

Principle of the motor, 113 

Principle of the three-wire sys¬ 
tem, 101. 

Principle of wiring a shunt motor, 
116. 

Protection of circuits, 169. 

Protection of insulation, 100. 

Purpose of analysis of wiring, 46. 

Purpose of equalizer, 181. 

Purpose of flexible steel-armored 
conduit, 135. 

Purpose of rotaries, 219. 

Purpose of series winding, 185. 

Purpose of two-phase currents, 
256- 

Purpose of wiring, 17. 

R 

Raising voltage, 259. 

Rating of lamps, 159 

Ratio of transformation, 259. 

Reactance, calculation of, 233. 

Rear view of switchboard, two- 
shunt machines, 177. 

Reasons for employing conduit, 
124. 

Recording wattmeter, 201, 281. 

Regulation and control of lights, 
167. 


INDEX 


309 


Regulation of EMF., 81. 

Reinforcement of trolley line, 
204. 

Relationship between coulombs 
and amperes, 20. 

Relationship between coulombs, 
coppers, and amperes, 20. 

Relationship expressed by Ohm’s 
law, 18. 

Relationship of watts, volts, and 
ampere, 38. 

Requirements for conduit, 141. 

Requirements for iron conduit, 
143- 

Requirements for steel-armored 
conduit, 143. 

Resistance and circular mils, 
32. 

Resistance and cross-section of 
wires, 61. 

Resistance and inductance com¬ 
pared, 236. 

Resistance effected by tempera¬ 
ture, 41. 

Resistance in multiple, 33. 

Resistance of equalizer bar, 183. 

Resistance of insulation, 94. 

Resistance of lamp measured 
cold, 93. 

Resistance of wires, 24. 

Resistance units, use of with 
voltmeter for multiplying volt¬ 
meter scale, 275. 

Rheostat, 171. 

Rheostat as a regulator, 83, 

Rheostatic regulation, 179. 


Risk in connecting shunt gener¬ 
ators, 174. 

Rotaries, application of, 220. 

Rotaries for power distribution, 
221. 

Rotaries in electric lighting, 254. 

Rotaries in power transmission, 
252. 

Rotary converters, 218. 

Rotor, 249. 

Rotor of motor, 250. 

Rubber-covered wires, 41. 

Rule for calculating equal re¬ 
sistances in multiple, 34. 

Rule for constructing wiring 
table, 54. 

S 

Safe operation of generators, 181- 

Saving in copper, 62. 

Schedule for wiring system, 140. 

Scott connection, two- to three- 
phase transformation, 269. 

Secondary two-phase, four-wire 
connecters, 264. 

Secondary two-phase, three-wire 
connecters, 265. 

Section of switchboard, 193. 

Self-starting alternating current 
motors, 256. 

Separate mains, 67. 

Separation of EMF. and C., 228. 

Series, coil of generator, 181- 

Series, electric lighting, 28- 

Series, fields, 184. 


3 IQ 


INDEX 


Series, field shunt resistance, 186. 

Series, wound motor, 113. 

Shunt dynamos, 83. 

Shunt generator, connections of, 
169. 

Shunt resistance of series field, 
186. 

Shunt wound motor, 113. 

Single- and double-pole circuit 
breakers, 192. 

Single-phase calculations, 243. 

Single-phase motors, 251. 

Single-phase transformer con¬ 
nected in multiple, 262. 

Single-phase transformer testing 
for accuracy of connections, 
262, 263. 

Single-phase wattmeter, 2-wire, 
283. 

Single-phase wattmeter, 3-wire, 
283. 

Sizes of wire and circular mils, 31. 

Sizes of wire calculated by rule, 
55- 

Size of wire for alternating cur¬ 
rent mains, 242. 

Size of wire for motors calcu¬ 
lated, 118. 

Size of wire with two- and three- 
wire systems, 105. 

Slate drilled for apparatus, 190. 

Soldering fluid, 151. 

Special insulation, 147. 

Speed of compound generators, 
182. 

Squirrel cage motors, 251. 


Star-star three-phase connection, 

266. 

Star and neutral for power and 
light, 267. 

Star and neutral, voltage be¬ 
tween, 267. 

Static transformers, 259. 

Station fires through lightning, 
208. 

State of motor, 250. 

Steel-armored conduit require¬ 
ments, 143. 

Steel-armored flexible cord, 136. 

Step-down transformers, 253,259. 

Step-up transformers, 253, 259. 

Strain on insulators, 215. 

Street railway, generator and 
feeder, switchboard sections, 
205. 

Street railway plants, 186. 

Street railway switchboard, 204. 

Sub-centers of distribution, 77. 

Sub-division of a railway board, 
204. 

Sub-station distribution, 255. 

Sub-stations, rotaries for, 255. 

Sub-stations, use of, 219. 

Switchboards, 168. 

Switchboard apparatus, 168. 

Switchboard design, 188. 

Switchboards for electrolytic 
work, 197. 

Switchboard for lighting, 176. 

Switchboard for street railway 
work, 204. 

Switchboard marble. 147. 


INDEX 


Switchboard, rear view of con¬ 
nections of two-shunt ma¬ 
chines, 177. 

Switchboard requirements, 156. 

Switchboard with control of 
floors, 178. 

Synchronous motors, 251. 

System of wiring for two floors, 

69. 

T 

Table of amperes in wiring and 
insulation resistance, 149. 

Table of asphaltic paper conduit, 
131- 

Table of brass-armored conduit, 
130- 

Table of copper and insulation 
resistance, 96. 

Table of cosines, 241. 

Table of coulombs and amperes, 
20. 

Table of different centers of dis¬ 
tribution, 74. 

Table of distance, watts, drop, 
and size, 62. 

Table of drop and circular mils 
for branches, 70. 

Table of drop and circular mils 
for feeders, 70. 

Table of drop and circular mils 
for mains, 70. 

Table of drop in a line, 24. 

Table of drop per 1,000 feet per 
ampere, 60. 


3il 

Table of efficiency and circular 
mils for motors, 120. 

Table of enameled iron conduit, 
130. 

Table of feet of wire and insula¬ 
tion resistance, 96. 

Table of flexible metallic conduit, 
132. 

Table of flexible steel-armored 
conduit, 137. 

Table of flexible woven conduit, 
132. 

Table of floors, outlets and pur¬ 
pose, 153. 

Table of gauge number and drop 
per 1,000 feet per ampere, 61. 

Table of horse power and effi¬ 
ciency, 119. 

Table of iron-armored conduit, 
129. 

Table of intermediate sizes of 
wire, 56. 

Table of lamp drop in Wiede¬ 
mann system, 49. 

Table of power factors, 245. 

Table of relationship of watts, 
volts, and amperes, 38. 

Table of resistance, cross-section, 
and length of wire, 26. 

Table of resistance and cross- 
section of wires, 25. 

Table of sections of switchboards, 
208. 

Table of sizes of wire, 55. 

Table of temperature coefficients, 
42. 


3 12 


INDEX 


Table of turns, speed, lines of 
force and volts, 81. 

Table of unequal resistance in 
multiple, 36. 

Table of volts and light efficiency 
163. 

Table of watts per candle power, 
159- 

Table of wiring, 50, 51, 52. 

Table showing effect of field 
changes on volts, 82. 

Table with amperes constant, 21. 

Table with ohms constant, 22. 

Table with volts constant, 21. 

Telegraph lines, insulation resist¬ 
ance of, 97. 

Temperature affecting resistance 
and drop, 41. 

Temperature coefficients, 42. 

Temperature use in transformers, 
273- 

Testing conduits, 87, 209. 

Testing Delta-delta three-phase 
transformer connections for 
accuracy, 268, 269. 

Testing for accuracy of trans¬ 
former connections, single¬ 
phase, 262, 263. 

Testing three-phase wattmeters, 
285. 

Testing with a magneto, 213. 

Testing with a voltmeter, 212. 

The alternating current, 121. 

The power factor, 238. 

The resistance box, 83. 

The three-wire system, 101. 


The wiring table, 50, 51, 52. 

The Wheatstone bridge, 87. 
Theory of the Wheatstone bridge, 
90. 

Three centers of distribution, 76. 
Three-phase alternate connec¬ 
tions, 257. 

Three-phase circulation of wire 
for, 247. 

Three-phase circuits, 245. 
Three-phase connections, Delta- 
delta, 268. 

Three-phase connections, star- 
star, 266. 

Three-phase Delt^ connections, 

268. 

Three-phase Delta-star connec¬ 
tions, 270. 

Three-phase motor connections, 

252. 

Three-phase system, 256. 
Three-phase wattmeter, 284. 
Three-wire panel boards, 155. 
Three-wire secondary two-phase 
transformation, 264. 

Three-wire system for lighting, 
101. 

Tools for conduit work, 138. 
Transformation ratio 259-260. 
Transformers—air-cooled, 272. 
Transformers, auto, 249. 
Transformer, diagram of primary 
and secondary connections, 
262. 

Transformer, diagram of two- 
phase connections, 264. 


INDEX 


313 


Transformer, energy loss, 260, 

261. 

Transformer, instantaneous flow 
of current, 263. 

Transformers multi-voltage taps, 
271. 

Transformers, oil-cooled, 272- 
3- 

Transformers, single-phase con¬ 
nected in multiple or parallel, 

262. 

Transformer, single-phase dia¬ 
gram, 259. 

Transformers, static, 259. 

Transformers temperature rise, 
273- 

Transformers, testing for accu¬ 
racy of connections, single¬ 
phase, 262, 263. 

Transformers, two-phase con¬ 
nections, 264. 

Transformers, step-down, 259, 
253- 

Transformers, step-up, 253, 259. 

Transformers, water-cooled, 273. 

Transformer, winding, 254. 

Transmission plant, elements of, 
253- 

Two-floor system of waring, 69. 

Two-phase alternator connec¬ 
tions, 257. 

Two-phase circuits determined, 
258. 

Two-phase lighting system, 255. 

Two-phase mains, calculation of, 
244. 


Two-phase motor connections, 
251. 

Two-phase transformer connec¬ 
tions, 264. 

Two- to three-phase transfor¬ 
mation, 269. 

Two-wire panel boards, 154. 

Two-wire system ground detect¬ 
or, 210. 

Two-wire 2 20-volt system, 103. 

Type of glass and effective light, 
164. 

Types of motors, 112. 

U 

Unarmored conduit, 128. 

Unbalanced three-wire system, 
104. 

Underwriters’ laws for panel 
boards, 155. 

Underwriters’ laws for switch¬ 
boards, 155. 

Unequal resistances in multiple, 
34- 

Unit of self-induction 236. 

Use of bridge, 91. 

Use of bus bars, 175. 

Use of chandeliers, 166. 

Using solder for joints, 151. 

V 

Value of capacity reactance, 234. 

Value of cos. of angle, 240. 


3H 


INDEX 


Value of induction reactance,233. 

Various power equipments, 219. 

Ventilation of New York Stock 
Exchange, 17. 

Voltage between neutral and 
star, 267. 

Voltage drop on ammeter shunt, 
277- 

Voltage, lowering, 259. 

Voltages, multi, 272. 

Voltage on two-phase, four-wire 
secondary, 264. 

Voltage on two-phase, three-wire 
secondary, 265. 

Voltage, raising, 259. 

Voltmeter and resistance units 
for multiplying voltmeter scale, 
275- 

Voltmeter, differential, 195. 

Voltmeter-multipliers, 275. 

Voltmeters, standard, 274. 

Volts lost and length of wire, 26. 

V or open delta connections, 266. 

W 

Waste of light through globes, 
164. 

Wattless current, 239. 

Wattmeter—curve-drawing, 281. 

Wattmeter—indicating, 281. 

Wattmeter, recording, 280-1. 

Wattmeter, two-wire, D. C., 281- 
282. 

Wattmeter, three-wire, D. C., 
282. 


Wattmeter, single-phase, two- 
wire, 283. 

Wattmeter, single-phase, two- 
wire, 283. 

Wattmeter, single-phase, three- 

wire, 283. 

Wattmeters testing for rotation, 
283, 284. 

Wattmeters, three-phase, 284. 

Watts per candle power, at low 
pressure, 163. 

Waves of alternating EMF., 
227. 

Weatherproof wire, 217. 

Weight of copper and efficiency 
of motor, 121. 

Weight of copper for mains, 249. 

Weight of copper and pressure, 
102. 

Weight of wire calculated, no. 

Wheatstone bridge, theory of, 90. 

Wheatstone bridge, resistances, 
89. 

Wiedemann system, 46, 47, 48, 
49> 5°- 

Wiedemann wiring analysed, 47, 
48. 

Wire, neutral, 266, 267. 

Wires, calculation of resistance 
of, 25. 

Wires, carrying capacity of, 40. 

Wires, cross-section and resist¬ 
ance, 25. 

Wires, rubber-covered, 41. 

Wire sizes for open and con¬ 
cealed work, 148. 


1 


INDEX 


Wires, underground, 125. 
Wiring defined, 15. 

Wiring formula, 30. 

Wiring by the Wiedemann 
system, 46, 47. 

Wiring for three-wire sys¬ 
tem, 108. 

Wiring for single-phase, 243. 
Wiling system for conduit, 

1 * 0 . 


315 

Wiring system, elements of, 
63- 

Wiring table developed, 52. 
Wiring table rule, 54. 

Wiring with steel-armored 
flexible conduit, 135. 
Winding of transformer, 254. 

Z 

Zero points in one cycle, 227. 


SUPPLEMENTARY INDEX 


Adjustable speed induction 
motor, 288. 

Advantages of induction 
motors, 286. 

Auto-transformer or compen¬ 
sator, 292. 

Calculating induction motor 
speed, 288. 

Compensator, internal wiring 
of, 295. 

Compensator, use of, 292. 
Connecting overload relay, 
293- 

Connections of three-phase 
motor, 291. 

Induction motor, adjustable 
speed, 288. 

Induction motor advantages, 

286. 

Induction motor, multi-speed, 

287. 

Induction motor speed, how 
controlled, 287. 

Induction motor, wiring, 290. 


Motor, three-phase slip ring 
wiring, 289. 

Multi-speed induction motor, 
287. 

Overload relay, connections 
of an, 293. 

Poles in induction motors, 
number of, 288. 

Relay, overload, 293. 

Relay, time limit, 294. 

Speed of induction motors, 
how to figure, 288. 

Three-phase motor and com¬ 
pensator wiring, 294. 

Three-phase motor connec¬ 
tions, 291. 

Time limit relay, 293. 

Two-phase, three-wire dia¬ 
gram, 291. 

Two-phase, four-wire dia¬ 
gram, 291. 

Wiring induction motor, 290. 

Wiring three-phase slip ring 
motor, 289. 





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PRACTICAL BOOKS FOR PRACTICAL MEN 

Any of these books will be sent prepaid 
to any part of the world, on receipt of 
price. Remit by Draft, Postal Order, 
Express Order or Registered Letter. 


Published and For Sale by 

TheN orman W.H enley Publishing Co. 

2 West 45th Street New York, U. S. A. 

1___ 













INDEX TO SUBJECTS 


Accidents . 27 

Air Brake .25, 26 

Arithmetic .15, 29, 38 

Automobiles ....3, 4, 5, 6, 7 
Automobile Charts «... 7 

Aviation . 8 

Batteries . 18 

Bevel Gears . 22 

Brazing and Soldering. 9 

Cams . 22 

Charts .7, 8, 9 

Chemistry . 21 

Civil Engineering . 29 

Coke . 10 

Compressed Air . 10 

Concrete.10, 11, 12, 13 

Cosmetics . 34 

Dictionaries . 14 

Dies—Metal Work ..13, 14 
Drawin g—Sketching 

Paper .14, 15 

Electric Bells . 16 

Electricity.. 15, 16, 17, 18,19 


Encyclopedia . 29 

F a c t o ry Management, 

etc. 19 

Ford Automobile. 6 

Fuel . 20 

Flying Machines . 8 

Gas Engines and Gas, 

20 , 21 , 22 

Gearing and Cams .... 22 

Hydraulics . 22 

Ice and Refrigeration.. 22 
Inventions—Patents ... 23 

Knots . 23 

Lathe Work.23, 24 

Link Motion . 25 

Liquid Air . 24 


Locomotive Engineering, 

24, 25, 26, 27 


Machine Shop Practice 


27, 29, 

30, 31 

Manual Training ... 


Marine Engineering . 

... 32 

Mechanical Magazine 

.. 28 

Mechanical Movements. 30 

Metal Turning . 

,.. 23 

Metal Work Dies ... 

.13, 14 

Mining . 


Moton Cycles .. 

...6, 7 

Patents and Inventions. 23 

Pattern Making. 


Perfumery . 


Plumbing ... 


Receipt Book. 

.35, 40 

Refrigeration and Ice.. 22 
Repairing Automobiles.. 6 

Rubber . 


Saws 

... 36 

Screw Cutting . 


Sheet Metal Work .. 

.13, 14 

Smoke Prevention ... 


Soldering . 


Starting Systems ..., 

... 5 

Steam Engineering. 36, 37, 38 
Stea~i Heating and Yen- 

tilation .. 


Steel . 

.38, 39 

Storage Batteries .... 


Switch Boards . 

.17, 19 

Tractor . 

.22, 39 

Turbines.. 


Ventilation ......... 

... 38 

Waterproofing ..... 


Welding . 


Wiring. 

.17, 18 

Wireless Telephones 

.. 19 


£ 2 ^ Any of these books will be sent prepaid to any 
part of the world, on receipt of price. 

RE MIT by Draft, Postal Money Order, Express Money 
Order, or by Registered Mail. 


2 



























































AUTOMOBILES—MOTORCYCLES 


The Modern Gasoline Automobile, Its Design, 
Construction, Operation. 

By Victor W. Page, M.S.A.E. This is the most complete, 
practical, and up-to-date treatise on gasoline automobiles and 
their component parts ever published. In the new revised 
and enlarged 1919 edition, all phases of automobile construc¬ 
tion, operation and maintenance are fully and completely 
described and in language anyone can understand. Every 
part of all types of automobiles, from light cyclecars to 
heavy motor trucks and tractors, are described in a thorough 
manner; not only the automobile, but every item of its 
equipment, accessories, tools needed, supplies and spare parts 
necessary for its upkeep, are fully discussed. It is clearly 
and concisely written by an expert familiar with every 
branch of the automobile industry and the originator of the 
practical system of self-education on technical subjects; it 
is a liberal education in the automobile art, useful to all who 
motor for either business or pleasure. Anyone reading the 
incomparable treatise is in touch with all improvements that 
have been made in motor car construction. All latest de¬ 
velopments, such as high speed aluminum motors and mul¬ 
tiple valve and sleeve valve engines, are considered in 
detail. The latest ignition, carburetor and lubrication prac¬ 
tice is outlined. New forms of change speed gears, and 
final power transmission systems, and all latest chassis im¬ 
provements, are shown and described. This book is used 
as a text in all leading automobile schools, and is conceded 
to be the standard treatise. The chapter on Starting and 
Lighting Systems has been greatly enlarged, and many 
automobile engineering features that have long puzzled lay¬ 
men are explained so clearly that the underlying principles 
can be understood by anyone. This book was first pub¬ 
lished six years ago, and so much new matter has been 
added to the book that it is nearly twice its original size. 
The only treatise covering various forms of war automobiles 
and recent developments in motor truck design, as well as 
pleasure cars. This book is not too technical for the layman 
nor too elementary for the more expert. It is an incom¬ 
parable work of reference for home or school. 6x9. Cloth, 
1,000 pages, nearly 1,000 illustrations, 12 folding plates. 


3 








Questions and Answers Relating to Modern Auto¬ 
mobile Construction, Driving and Repair. 

By Victor W. Page. A self-educator on automobiling with¬ 
out an equal. This practical treatise consists of a series of 
thirty-seven lessons, covering with over 2,000 questions and 
their answers—the automobile, its construction, operation 
and repair. The subject matter is absolutely correct and 
explained in simple language. If you can’t answer all of 
the following questions, you need this work. The answers 
to these and 2,000 more are to be found in its pages. 

Give the name of all important parts of an automobile 
and describe their functions. Describe action of latest types 
of kerosene carburetors. What is the difference between a 
“double” ignition system. and a “dual” ignition system? 
Name parts of an induction coil. How are valves timed? 
What is an electric motor starter and how does it work? 
What are advantages of worm drive gearing? Name all 
important types of ball and roller bearings. What is a 
“three-quarter” floating axle? What is a two-speed axle? 
What is the Vulcan electric gear shift? Name the causes 
of lost power in automobiles. Describe all noises due to 
deranged mechanism and give causes. How can you adjust 
a carburetor by the color of the exhaust gases? What causes 
“popping” in the carburetor? What tools and supplies are 
needed to equip a car? How do you drive various makes 
of cars? What is a differential lock and where is it used? 
Name different systems of wire wheel construction. What 
is a “positive” drive differential? etc., etc. Answers every 
question asked relating to the modern automobile. A popu« 
lar work at a popular price. 5Cloth, 650 pages, 
392 illustrations, 3 folding plates. Revised Edition just 
published. Price, $2.50 

How to Run an Automobile. 

By Victor W. Pag£. This treatise gives concise instruc¬ 
tions for starting and running all makes of gasoline auto¬ 
mobiles, how to care for them, and gives distinctive features 
of control. Describes every step for shifting gears, con¬ 
trolling engine, etc. Among the chapters contained are: 
I. Automobile Parts and Their Functions. II. General 
Starting and Driving Instructions. III. Typical 1919 Con¬ 
trol Systems—Care of Automobiles. Thoroughly illustrated. 
178 pages, 72 illustrations. Price, $1.25 

The Automobilist’s Pocket Companion and Ex¬ 
pense Record.. 

By Victor W. Pag&. This book is not only valuable as a 
convenient cost record, but contains much information of 
value to motorists. Includes a condensed digest of auto laws 
of all States, a lubrication schedule, hints for care of storage 
battery and care of tires, location of road troubles, anti¬ 
freezing solutions, horsepower table, driving hints and many 
useful tables and recipes of interest to all motorists. Not a 
technical book in any sense of the word, just a collection of 
practical facts in simple language for the everyday motorist. 
Convenient pocket size. Price, $1.00 




4 


Gasoline and Kerosene Carburetors, Construction, 
Installation and Adjustment. 

By Capt. V. W. Page. All leading types of carburetors are 
described in detail, special attention being given to the forms 
devised to use the cheaper fuels such as kerosene. Carburetion 
troubles, fuel system troubles, carburetor repairs and instal¬ 
lation, electric primers and economizers, hot spot manifolds 
and all modern carburetor developments are considered in a 
thorough manner. Methods of adjusting all types of car¬ 
buretors are fully discussed as well as suggestions for secur¬ 
ing maximum fuel economy and obtaining highest engine 
power. 250 pages, 89 illustrations. Price, $2.00 


Starting, Lighting and Ignition Systems. 

By Victor W. Page. A practical treatise on modern starting 
and ignition system practice. This practical volume has been 
written with special reference to the requirements of the 
nontechnical reader desiring easily understood explanatory 
matter relating to all types of automobile ignition, starting 
and lighting systems. It can be understood by anyone, even 
without electrical knowledge, because elementary electrical 
principles are considered before any attempt is made to dis¬ 
cuss features of the various systems. These basic principles 
are clearly stated ana illustrated with simple diagrams. All 
the leading systems of starting, lighting and ignition have 
been described and illustrated with the cooperation of the 
experts employed by the manufacturers. Wiring diagrams 
are shown in both technical and nontechnical forms. All 
symbols are fully explained. Complete data is given for 
locating troubles in all systems, the various steps being con¬ 
sidered in a logical, systematic manner, that can be easily 
followed by those without expert electrical knbwledge. All 
ignition systems receive full consideration, starting with the 
simplest battery and coil forms found on early cars to the 
modern short-contact timer and magneto methods used with 
the latest eight and twelve-cylinder motors. Every ignition, 
starting or lighting system component is considered individ¬ 
ually, and full directions are given for making all repairs. 
This book is unusually complete, as it also includes descrip¬ 
tions of various accessories operated by electric current, such 
as electrical gear shifts, brake actuation, signaling devices,, 
vulcanizers, etc. Nearly 500 pages. 297 specially made en¬ 
gravings. New Edition. Price, $2.50 


Automobile Welding with the Oxy-Acetylene 
Flame. 

By M. Keith Dunham. Explains in a simple manner ap¬ 
paratus to be us'ed, its care, and how to construct necessary 
shop equipment. Proceeds then to the actual welding of all 
automobile parts, in a manner understandable by everyone. 
Gives principles never to be forgotten . This, book is of ut¬ 
most value, since the perplexing problems arising when metal 
is heated to a melting point are fully explained and the 
proper methods to overcome them shown. 167 pages, fully 
illustrated. Price, $1.50 


5 


Automobile Repairing Made Easy. 

By Victor W. Page. A thoroughly practical book contain 
ing complete directions for making repairs to all parts of the 
motor car mechanism. Written in a thorough but non¬ 
technical manner. Gives olans for workshop construction, 
suggestions for equipment, power needed, machinery and 
tools necessary to carry on business successfully. Tells how 
to overhaul and repair all parts of all automobiles. The 
inf rmation given is founded on practical experience, every¬ 
thing is explained so simply that motorists and students can 
acquire a full working knowledge of automobile repairing. 
Other works dealing with repairing cover only certain parts 
of the car—this work starts with the engine, then considers 
carburetion, ignition, cooling and lubrication systems. The 
clutch, change speed gearing and transmission system are 
considered in detail. Contains instructions for repairing 
all types of axles, steering gears and other chassis parts. 
Manv tables, short cuts in figuring and rules of practice 
are given for the mechanic. Exnlains fully valve and mag¬ 
neto timing, “tuning” engines, systematic location of trouble, 
repair of ball and roller bearing, shop kinks, first aid to 
injured and a multitude of subjects of interest to all in the 
garage £.nd repair business. All illustrations are especially 
made for this book, and are actual’photographs or reproduc* 
tions of engineering drawings. This book also contains 
Special Instructions on Electric Starting, Lighting and Igni¬ 
tion Systems, Tire Repairing and Rebuilding, Autogenous 
Welding, Brazing and Soldering, Heat Treatment of Steel, 
Latest Timing Practice, Eight and Twelve-Cylinder Motors, 
etc., etc. You will never “Get Stuck” on a Job if you own 
this book. 1,000 specially made engravings on 500 plates. 
1,056 pages (5j4x8). 11 folding plates. Price, $4.00 

The Model T Ford Car, Its Construction, Opera¬ 
tion and Repair, Including the Ford Farm 
Tractor. 

By Victor W. Page. This is the most complete and prac¬ 
tical instruction book ever published on the Ford car. A 
high grade, cloth bound book, printed on the best paper, 
illustrated by specially made drawings and photographs. All 
parts of the Ford Model T Car are described and illustrated 
in a comprehensive manner—nothing is left for the reader 
to guess at. The construction is fully treated and operating 
principle made clear to everyone. Complete instructions for 
driving and repairing are given. Every detail is treated in 
a non-technical yet thorough manner. To the 1919 Revised 
Edition matter has been included on the Ford Truck and 
Tractor Conversion Sets and Genuine Ford Tractor. All 
parts are described. All repair processes illustrated and 
fully explained. Written so all can understand—no theory, 
no guesswork. New Edition. 106 illustrations, 310 pages, 
2 large folding plates. Price, $1.50 

Motorcycles, Side Cars and Cyclecars, Their 
Construction, Management and Repair. 

By Victor W. PAbfi. Describes fully all leading types of 
machines, their design, construction, maintenance, operation 
and repair. 550 pages. 350 specially made illustrations. 5 
folding plates. New Edition. Price, $2.00 


6 


Automobile Charts 

By VICTOR W. PAGE, M.S.A.E. 

THE POPULAR AUTOMOBILE SERIES 
UNIFORM SIZE—24"x 38"—PRICE 35 CENTS EACH 


Location of Gasoline Engine Troubles Made Easy. 

This chart shows clearly all parts of a typical four-cylinder 
gasoline engine of the four-cycle type. It simplifies location of all 
engine troubles. No details omitted. "Price 35 cent9 


Location of Carburetion Troubles Made Easy. 

It shows clearly how to find carburetion troubles and names 
all defects liable to exist in the various parts. Instructions are 
given for carburetor adjustment. Price 35 cents' 


Location of Ignition System Troubles Made Easy. 

In this chart all parts of a typical double ignition system using 
battery and magneto current are shown, and suggestions are given 
for readily finding ignition troubles and eliminating them when 
found. Price, 35 cents 


Location of Cooling and Lubricating Troubles. 

This is a combination chart showing all components of the ap¬ 
proved form of water cooling group as well as a modern engine 
lubrication system. It shows all points where defects exist that 
may result in engine overheating, both in cooling and oiling systems. 

Price, 35 cents 

Lubrication of the Motor Car Chassis. 

This chart presents the plan view of a typical six-cylinder chassis 
of standard design and outlines all important bearing points re¬ 
quiring lubrication, and is a valuable guide to the correct lubrication 
of any modern car. A practical chart for all interested in motor 
car maintenance. Price, 35 cents* 

While each chart is complete in itself, the set covers all maintenance 
instructions for the entire automobile. Sold singly. Securely wrapped . 


Location of Starting and Lighting System Faults. 

The most complete chart yet devised, showing all parts of the 
modern automobile starting, lig ting and ignition systems, giving in¬ 
structions for systematic location of all faults in wiring, lamps; 
motor or generator, switches and all other units. Invaluable to 
motorists, chauffeurs and repairmen. Size 24 x 38 inches. 

, Price, 35 cents 

Location of Ford Engine Troubles Made Easy. 

Chart showing clear sectional views depicting all portions of 
the Ford power plant and auxiliary groups. It outlines clearly 
all parts of the engine, fuel supply systems, ignition group and 
cooling system, that are apt to give trouble, detailing all derange¬ 
ments that are liable to make an engine lose power, start hard, or 
work irregularly. This chart simplifies location of all engine faults. 
Size 25 x 38 inches. Price, 35 cents 


Location of Motorcycle Troubles Made Easy. 

This chart simplifies location of all power-plant troubles and 
will prove of value to all who have to do with the operation, repair 
or sale of motorcycles. No details omitted. Size 30 x 20 inches. 

Price, 35 cents 


7 






AVIATION 


A B C of Aviation. 

By Capt. V. W. Page. This book describes the basic prin¬ 
ciples of aviation, tells bow a balloon or dirigible is made 
and why it floats in the air. Describes how an airplane flies. 
It shows in detail the different parts of an airplane, what 
they are'and what they do. Describes all types of airplanes 
and how they differ in construction; as well as detailing the 
advantages and disadvantages of different types of aircraft. 
It includes a complete dictionary of aviation terms and clear 
drawings of leading airplanes. The reader will find simple 
instructions for unpacking, setting up and rigging airplanes. 
A full description of airplane control principles is given and 
methods of flying are discussed at length. 

This Book answers every question one can ask about mod¬ 
ern aircraft, their construction and operation. A self educa¬ 
tor on aviation without an equal. 275 pages, 130 specially 
made illustrations with 7 plates. Price, $2.50 

Aviation Engines—Design; Construction; Repair. 

By Lieut. Victor W. Page, Aviation Section, S.C.U.S.R. 
This treatise, written by a recognized authority on all of 
the practical aspects of internal combustion engine construc¬ 
tion, maintenance and repair, fills the need as no other book 
does. The matter is logically arranged; all descriptive mat¬ 
ter is simply expressed and copiously illustrated, so that any¬ 
one can understand airplane engine operation and repair even 
if without previous mechanical training. This work is in¬ 
valuable for anyone desiring to become an aviator or aviation 
mechanician. 

The latest rotary types, such as the Gnome Monosoupape, 
and LeRhone, are fully explained, as well as the recently 
developed Vee and radial types. The subjects of carburetion, 
ignition, cooling and lubrication also are covered in a thorough 
manner. The chapters on repair and maintenance are dis¬ 
tinctive and found in no other book on this subject. Not a 
technical book, but a practical, easily understood work of 
reference for all interested in aeronautical science. 576 
pages, 253 illustrations. Price, Net, $3.00 

Glossary of Aviation Terms — English-French; 
French-English. 

A complete glossary of practically all terms used in aviation, 
having lists in both French and English with equivalents in 
either language compiled by Lieuts. Victor W. Page, A.S., 
S.C.U.S.R., and Paul Montariol, of the French Flying 
Corps. Price, Net, $1.00 

Aviation Chart—Location of Airplane Power 
Plant Troubles Made Easy. 

By Lieut. Victor W. Pag£, A.S., S.C.U.S.R. A large chart 
outlining all parts of a typical airplane power plant, showing 
the points where trouble is apt to occur and suggesting 
remedies for the common defects. Intended especially for 
aviators and aviation mechanics on school and field duty. 

Price, 50 eents 


8 




BRAZING AND SOLDERING 


Brazing and Soldering. 

By James F. Hobart 1 he only book that shows vou just 
how to hand e any job of brazing or soldering that comes 

along, it tells 3 r ou what mixture to use, how to make a 

furnace if you need one._ Full of valuable kinks. The fifth 

edition ot this book has just been published, and to it much 

new matter and a large number of tested formulas for all 
kinds of solders and fluxes have been added. Price, 35c. 


CHARTS 


Aviation Chart — Location of Airplane Power 
Plant Troubles Made Easy. 

By Lieut. Victor VV. Page, A.S., S.C.U.S.R. A large chart 
outlining all parts of a typical airplane power plant, showing 
the points where trouble is apt to occur and suggesting 
remedies for the common defects. Intended especially for 
aviators and aviation mechanics on school and field duty. 

Price, 50 cents* 

Modern Submarine Chart—With 200 Parts Num¬ 
bered and Named. 

A cross-section view, showing clearly and distinctly all the 
interior of a submarine of the latest type. No details omitted— 
everything is accurate and to scale. This chart is really an 
encyclopedia of a submarine. Price, 25 cents 

Box Car Chart. 

A chart showing the anatomy of a box car, having every part 
of the car numbered and its proper name given in a reference 

list. Price, 25 cents 

Gondola Car Chart. 

A chart showing the anatomy of a gondola car, having every 
part of the car numbered and its proper reference name given 
in a reference list. Price, 25 cents 

Passenger Car Chart. 

A chart showing the anatomy of a passenger car, having 
every part of the car numbered and its proper name given 
in a reference list. Price, 25 cents 

Steel Hopper Bottom Coal Car. 

A chart showing the anatomy of a steel hopper bottom coal 
car, having every part of the car numbered and its proper 

name given in a reference list. Price, 25 cents 

Tractive Power Chart. 

A chart whereby you can find the tractive power or drawbar 
pull of any locomotive without making a figure. Shows what 
cylinders are equal, how driving wheels and steam pressure 
affect the power. What sized engine you need to exert a 
given drawbar pull or anything you desire in this line. 

Price, 50 cents 


9 







Horse-power Chart. 

Shows the horse-power of any stationary engine without 
calculation. No matter what the cylinder diameter of stroke, 
the steam pressure or cut-oft, the revolutions, or whether 
condensing or non-condensing, it’s all there. Easy to use,, 
accurate and saves time and calculations. Especially useful 
to engineers and designers. Price, 50 cents 

Boiler Room Chart. 

By George L. Fowler. A chart—size 14 x 28 inches—showing 
in isometric perspective the mechanisms belonging in a modern 
boiler room. This chart is really a dictionary of the boiler 
room—the names of more than 200 parts being given. 

Price, 25 cent# 

COKE 


Coke—Modern Coking Practice, Including An¬ 
alysis of Materials and Products. 

By J. E. Christopher and T. H. Byrom. This, the standard 
work on the subject, has just been revised and is now 
issued in two volumes. It is a practical work for those en¬ 
gaged in Coke manufacture and the recovery of By-products. 
Fully illustrated with folding plates. It has been the aim 
of the authors, in preparing this book, to produce one which 
shall be of use and benefit to those who are associated with, 
or interested in, the modern developments of the industry. 
Among the chapters contained in Volume I are: Introduc¬ 
tion; Classification of Fuels; Impurities of Coals; Coal 
Washing; Sampling and Valuation of Coals, etc.; Chlorifie 
Power of Fuels; History of Coke Manufacture; Develop¬ 
ments in Coke Oven Design; Recent Types of Coke Ovens; 
Mechanical Appliances at Coke Ovens; Chemical and Physi¬ 
cal Examination of Coke. Volume II covers By-products. 
Each volume is fully illustrated, with folding plates. 

Price, $3.00 per volume 

COMPRESSED AIR 


Compressed Air in all Its Applications. 

By Gardner D. Hiscox. This is the most complete book on 
the subject of air that has ever been issued, and its thirty-five 
chapters include about every phase of the subject one can 
think of. It may be called an encyclopedia of compressed 
air. It is written by an expert, who, in its 665 pages, has 
dealt with the subject in a comprehensive manner, no phase 
of it being omitted. Over 500 illustrations. Fifth Edition, 
revised a^d enlarged. Cloth bound, $0.00. Half Morocco, 

Price, $7.5(1 

CONCRETE 


Concrete Wall Forms. 

By A. A. Houghton. A new automatic wall clamp, is illus¬ 
trated with working drawings. Other types of wall forms, 
clamps, separators, etc., are also illustrated and explained. 

Price, (50 ceut» 


10 








Concrete Floors and Sidewalks. 

By A. A. Houghton. The molds for molding squares, hex¬ 
agonal and many other styles of mosaic floor and sidewalk 
blocks are fully illustrated and explained. Price, 00 cents 

Practical Concrete Silo Construction. 

By A. A. Houghton. Complete working drawings and speci¬ 
fications are given for several styles of concrete silos, with 
illustrations of molds for monolithic and block silos. The 
tables, data, and information presented in this book are 
of the utmost value in planning and constructing all forms 
of concrete silos. Price, 60 cents 

Molding Concrete Bath Tubs, Aquariums and 
Natatoriums. 

By A. A. Houghton. Simple molds and instruction are given 
for molding different styles of concrete bath tubs, swimming 
pools, etc. Price, 60 cents 

Molding Concrete Chimneys, Slate and Roof Tiles. 

By A. A. Houghton. The manufacture of all types of con¬ 
crete slate and roof tile is fully treated. Valuable data on 
all forms of reinforced concrete roofs are contained within 
its pages. The construction of concrete chimneys by block 
and monolithic systems is fully illustrated and described. 
A number of ornamental designs of chimney construction with 
molds are shown in this valuable treatise. 60 cents 


Molding and Curing Ornamental Concrete. 

By A. A. Houghton. The proper proportions of cement 
and aggregates for various finishes, also the methods of thor¬ 
oughly mixing and placing in the molds, are fully treated. 
An exhaustive treatise on this subject that every concrete 
worker will find of daily use and value. Price, 60 cents 


Concrete Monuments, Mausoleums and Burial 
Vaults. 

By A. A. Houghton. The molding of concrete monuments 
to imitate the most expensive cut stone is explained in this 
treatise, with working drawings of easily built molds. Cutting 
inscriptions and designs is also fully treated. 60 cents 


Concrete Bridges, Culverts and Sewers. 

By A. A. Houghton. A number of ornamental concrete 
bridges with illustrations of molds are given. A collapsible 
center of core for bridges, culverts and sewers is fully illus¬ 
trated with detailed instructions for building. 60 cents 

Constructing Concrete Porches. 

By A. A. Houghton. A number of designs with working 
drawings of molds are fully explained so any one can easily 
construct different styles of ornamental concrete porches 
without the purchase of expensive molds. Price, 60 cents 

11 


Molding Concrete Flower Pots, Boxes, Jardi¬ 
nieres, Etc. 

By A. A. Houghton. The molds for producing many original 
designs of flower pots, urns, flower boxes, jardinieres, etc., 
are fully illustrated and explained, so the worker can easily 
construct and operate same. • Price, 60 cents 

Molding Concrete Fountains and Lawn Orna¬ 
ments. 

By A. A. Houghton. The molding of a number of designs 
of lawn seats, curbing, hitching posts, pergolas, sun dials and 
other forms of ornamental concrete, for the ornamentation 
of lawns and gardens, is fully illustrated and described. 60c. 

Concrete on the Farm and in the Shop. 

By H. Colvin Campbell. This is a new book from cover 
to cover, illustrating and describing in plain, simple language 
many of the numerous appliances of concrete within the 
range of the home worker. Among the subjects treated are: 
Principles- of reinforcing; methods of protecting concrete so 
as to insure proper hardening; home-made mixers; mixing 
by hand and machine; form construction, described and 
illustrated by drawings and photographs; construction of 
concrete walls and fences; concrete fence posts; concrete 
gate posts; corner posts; clothes line posts; grape arbor 
posts; tanks; troughs; cisterns: hog wallows; feeding floors 
and barnyard pavements; foundations; well curbs and plat¬ 
forms; indoor floors; sidewalks; steps; concrete hotbeds and 
cold frames; concrete slab roofs; walls for buildings; repairing 
leaks in tanks and cisterns; and all topics associated with 
these subjects as bearing upon securing the best results from 
concrete are dwelt upon at sufficient length in plain every-day 
English so that the inexperienced person desiring to under¬ 
take a piece of concrete construction can, by following the 
directions set forth in this book, secure 100 per cent success 
every time.. A number of convenient and practical tables 
for estimating quantities, and some practical examples, are 
also given. 150 pages, 51 illustrations. Price, $1.06 

Concrete From Sand Molds. 

By A. A. Houghton. A practical work treating on a process 
which has heretofore been held as a trade secret by the 
few who possessed it, and which will successfully mold every 
and any class of ornamental concrete work. The process 
of molding concrete with sand molds is of the utmost practical 
value, possessing the manifold advantages of a low cost of 
molds, the ease and rapidity of operation, perfect details 
to all ornamental designs, density and increased strength 
of the concrete, perfect curing of the work without attention 
and the easy removal of the molds regardless of any under¬ 
cutting the design may have. 192 pages. Fullv illustrated. 
Cloth. Price, $2.00 

Ornamental Concrete Without Molds. 

By A. A. Houghton. The process for making ornamental 
concrete without molds has long been held as a secret, and 
now, for the first time, this process is given to the public. 
The book reveals the secret and is the only book published 


12 


*Yvmch explains a simple, practical method whereby the con* 
Crete worker is enabled, by employing wood and metal tem¬ 
plates of. different designs, to mold or model in concrete 
any cornice, archivolt, column, pedestal, base cap, urn or 
pier in a monolithic form—right upon the job. These may 
be molded in units or blocks, and then built up to suit the 
specifications demanded. This work is fully illustrated, with 
detailed engravings. Cloth. Price, $2.00 

Popular Handbook for Cement and Concrete 
Users. 

By Myron H. Lewis. Everything of value to the concrete 
user is contained, including kinds of cement employed in 
construction, concrete architecture, inspection and testing, 
waterproofing, coloring and painting, rules tables, working 
and cost data.. The book comprises thirty-three chapters. A 
valuable addition to the library of every cement and concrete 
user. Cloth, 430 pages, 126 illustrations. Price, $3.00 

Waterproofing Concrete. 

By Myron H. Lewis. Modern methods of waterproofing 
•concrete and other structures. A condensed statement of the 
principles, rules and precautions to be observed in water¬ 
proofing and damp-proofing structures and structural materials. 
Paper binding. Illustrated. Second Edition. 60 cents 


DIES—METAL WORK 


Dies; Their Construction and Use for the Modern 
Working of Sheet Metals. 

By J. V. Woodworth. A new book by a practical man, for 
those who wish to know the latest practice in the working 
of sheet metals. It shows how dies are designed, made and 
used, and those who are engaged in this line of work can 
secure many valuable suggestions. Sixth revised edition. 525 
illustrations, 394 pages. Cloth. Price, $3.50 

Punches, Dies and Tools for Manufacturing in 
Presses. 

By J. V. Woodworth. An encyclopedia of die-making, 
punch-making, die-sinking, sheet-metal working, and making 
of special tools, subpresses, devices and mechanical, combina¬ 
tions for punching, cutting, bending, forming, piercing, draw¬ 
ing, compressing, and assembling sheet-metal parts and also 
articles of other materials in machine tools. This is a dis¬ 
tinct work from the author’s book entitled “Dies; Their 
Construction and Use.” 500 pages, 700 engravings. Second 
edition. Cloth. Price, $4.50 

Drop Forging, Die-Sinking and Machine-Form¬ 
ing of Steel. 

By J. V. Woodworth. The processes of die-sinking and 
force-making, which are thoroughly described and illustrated 
in this admirable work, are rarely to be found explained in 
such a clear and concise manner as is here set forth.. The 
process of die-sinking i elates to the engraving or sinking 


13 




©f the female or lower dies, such as are used for drop 
forgings, hot and cold machine forging, swedging and the 
press working of metals. The process of force-making relates 
to the engraving or raising of the male or upper dies used 
in producing the lower dies for the press-forming and 
machine-forging of duplicate parts of metal. The book con¬ 
tains eleven chapters, and the information contained in these 
chapters is just what will prove most valuable to the forged- 
metal worker. 304 detailed illustrations. 341 pages, cloth. 

Price, $3.00 


DICTIONARIES 


Aviation Terms—English-French; French-Eng- 

lish. 

A complete glossary of practically all terms used in aviation, 
having lists in both French and English with equivalents in 
either language. A very valuable book compiled by Lieuts. 
Victor W. Page and Paul Montariol. Price, $1.00 

Standard Electrical Dictionary. 

By Prof. T. O’Conor Sloane. Just issued an entirely 
new edition brought up to date and greatly enlarged—as a 
reference book this work is beyond comparison as it contains 
over 700 pages, nearly 500 illustrations, and definitions of 
about 6,000 distinct words, terms and phrases. The defini¬ 
tions are terse and concise and includes every term used 
in electrical science. 

In its arrangement and typography the book is very con¬ 
venient. The word or term defined is printed in black faced 
type which readily catches the eye, while the body of the 
page is in smaller but distinct type. The definitions are well 
worded, and so as to be understood by the non-technical 
reader. The general plan is to give an exact, concise defini¬ 
tion, and then amplify and explain in a more popular way. 
Synonyms are also given, and references to other words 
and phrases are made. This work is absolutely indispensable 
to all in any way interested in electrical science, from the 
higher electrical expert to the everyday electrical workman. 
In fact, it should be in the possession of all who desire to 
keep abreast with the progress of this branch of science. 
Fifteenth enlarged edition. Nearly 800 pages and nearly 
400 illustrations. Price $5.00' 


DRAWING—SKETCHING PAPER 


Linear Perspective Self-Taught. 

By Herman T. C. Kraus. This work gives the theory and 
practice of linear perspective, as used in architectural, engi¬ 
neering and mechanical drawings. The arrangement of 
the book is good* the plate is on the left-hand, while the de¬ 
scriptive text follows on the opposite page, so as to be readily 
referred to. A self-explanatory linear perspective chart is 
included in the second revised edition. Cloth. Price, $2.50 


14 










Mechanical Drawing and Elementary 
Machine Design. 


By F. L. Sylvester, M.E., Draftsman, with additions by Erik 
Oberg, associate editor of “Machinery.” A practical ele¬ 
mentary treatise on Mechanical Drawing and Machine De- 
s ig n, compnsmg the first principles of geometric and mechan¬ 
ical drawing, workshop mathematics, mechanics, strength of 
materials and the calculation and design of machine details, 
compiled for the use of practical mechanics and young drafts¬ 
men. 330 pages, 215 engravings, cloth. Price, $2.50 


A New Sketching Paper. 

A new specially ruled paper to enable you to make sketches 
or drawings in isometric perspective without any figuring or 
fussing. It is being used for shop details as well as for 
assembly drawings, as it makes one sketch do the work of 
three, and no workman can help seeing just what is wanted. 
Pads of 40 sheets, 6x9 inches, Price, 25c.; 9x12 inches. 
Price, 50c.; 12x18 inches, Price, $1.00. 


Practical Perspective. 

By Richards and Colvin. Shows just how to make all kinds- 
of mechanical drawings in the only practical perspective 
isometric. Makes everything plain so that any mechanic can 
understand a sketch or drawing in this way. Saves time in 
the drawing room and mistakes in the shops. Contains prac¬ 
tical examples of various classes of work. Third edition. 
Limp cloth. Price, (.0 


ELECTRICITY 


Arithmetic of Electricity. 

By Prof. T. O’Conor Sloane. A practical treatise on elec¬ 
trical calculations of all kinds reduced to a series ot rules, 
all of the simplest forms, and involving only ordinary arith¬ 
metic; each rule illustrated by one or more practical problems 
with detailed solution of each one. This book is classed 
among the most useful works published on the science of 
electricity, covering as it does the mathematics of electricity 
in a manner that will attract the attention of those who are 
not familiar with algebraical* formulas. 160 pages. Twenty- 
first edition. Cloth. Price, $1.00 

Dynamo Building for Amateurs, or How to Con¬ 
struct a Fifty Watt Dynamo. 

By Arthur J. Weed. A practical treatise showing in detail 
the construction of a small dynamo or motor, the entire 
machine work of which can be done on a small foot lathe. 
Dimensioned working drawings are given for each piece of 
machine work, and each operation is clearly described. This 
machine, when used as a dynamo, has an output of fifty 
watts; when used as a motor it will drive a small drill press 
or lathe. It can he used to drive a sewing machine on any 
and all ordinary work. The book is illustrated with more 
than sixty original engravings showing the actual construction 
of the different parts. Price, Clotn, $1.0P 


15 




Electric Bells. 

By M. B. Sleeper. A complete treatise for the practical 
worker in installing, operating and testing bell circuits, 
burglar alarms, thermostats and other apparatus used with 
electric bells. Both the electrician and the experimenter will 
find in this book new material which is essential in their 
work. Tools, bells, batteries, unusual circuits, burglar alarms, 
annunciators, systems, thermostats, circuit breakers, time 
alarms, and other apparatus used in bell circuits are de¬ 
scribed from the standpoints of their application, construc¬ 
tion, and repair. The detailed instructions for building the 
apparatus will appeal to the experimenter particularly. The 
practical worker will find the chapters on Wiring Calculation 
of Wire Sizes and Magnet Windings, Upkeep of Systems 
and the Location of Faults of the greatest value in their 
work. 124 pages. Fully illustrated. Price, 60 cents 

Commutator Construction 

By Wm. Baxter, Jr. The business end of dynamo or motor 
of the direct current type is the commutator. This book goes 
into the designing, building and maintenance of commutators, 
shows how to locate troubles and how to remedy them; 
everyone who fusses with dynamos needs this. Fourth edi¬ 
tion. Price, 35 cents 

Experimental Wireless Stations. 

By P. E. Edelman. New enlarged 1919 edition just issued, 
strictly up to date, correct and complete. This book tells how 
to make apparatus to not only hear all telephoned radio 
messages, but also how to make simple equipment that works 
for transmission over reasonably long distances. Then there 
is a host of new information included. The first and only 
book to give you all the recent important radio improve¬ 
ments, some of which have never before been published. 
24 chapters. 161 illustrations. Price, $2.00 

Construction of a Transatlantic Wireless Receiv¬ 
ing Set. 

By L. G. Pacent and T. S. Curtis. A work for the Radio 
student who desires to construct and operate apparatus that 
will permit of the reception of messages from the large 
stations in Europe with an aerial of amateur proportions. 36 
pages. 23 illustrations, cloth. Price, 35 cents 

* Electric Toy Making, Dynamo Building and 
Electric Motor Construction. 

This work treats of the making at home of electrical toys, 
electrical apparatus, motors, dynamos and instruments in 
general and is designed to bring within the reach of young 
and old the manufacture of genuine and useful electrical 
appliances. 210 pages, cloth. Fully illustrated. Twentieth 
edition, enlarged. Price, $1.00 

Experimental High Frequency Apparatus, How 
to Make and Use It. 

By Thomas Stanley Curtis. 69 pages, illustrated. 

Price 50 cents 


16 


Electrician’s Handy Book. 

By Prof. T. O’Conor Sloane. This work has just been 
revised and much enlarged. It is intended for the practical 
electrician who has to make things go. The entire field of 
electricity is covered within its pages. It is a work of the 
most modern practice, written in a clear, comprehensive 
manner, and covers the subject thoroughly, beginning at the 
A B C of the subject, and gradually takes you to the more 
advanced branches of the science. It teaches you just what 
you should know about electricity. A practical work for the 
practical man. Contains forty-eight chapters. 

The publishers consider themselves fortunate in having 
secured the services of such a well and favorably known 
writer as Prof. Sloane, who has with the greatest care com¬ 
pleted a master work in concise form on this all important 
subject. 600 engravings, 840 pages, handsomely bound in 
cloth. Fifth edition. Price, $4.00 

Electricity Simplified. 

By Prof. T. O’Conor Sloane. The object of ‘Electricity 
Simplified” is to make the subject as plain as possible and 
to show what the modern conception of electricity is; to 
show how two plates of different metals immersed in acid 
can send a message around the globe; to explain how a 
bundle of copper wire rotated by a steam engine can be the 
agent in lighting our streets, to tell what the volt, ohm and 
ampere are, and what high and low tension mean; and to 
answer the questions that perpetually arise in the mind in 
this age of electricity. 172 pages. Illustrated. Thirteenth 
edition. Cloth. Price, $1.00 

Electric Wiring, Diagrams and Switchboards. 

By Newton Harrison, with additions by Thomas Poppe. 
This is the only complete work issued showing and telling 
you what you should know about direct and alternating cur¬ 
rent wiring. The work is free from advanced technicalities 
and mathematics, arithmetic being used throughout. It is in 
every respect a handy, well-written, instructive, comprehen¬ 
sive volume on wiring for the wireman, foreman, contractor 
or electrician. Second revised edition. 303 pages, 130 illu¬ 
strations. Cloth. Price, $2.00 

House Wiring. 

By Thomas W. Foppe. Describing and illustrating up-to-date 
methods of installing electric light wiring. Contains just the 
information needed for successful wiring of a building. 
Fully illustrated with diagrams and plans. It solves all wiring 
problems and contains nothing that conflicts with the ruling! 
of the National Board of Fire Underwriters. Third edition 
revised and enlarged. 125 pages, fully illustrated, flexible 
cloth. Price, 75 cents 

High Frequency Apparatus, Its Construction and 
Practical Application. 

By Thomas Stanley Curtis. The most comprehensive and 
thorough work on this interesting subject ever produced. 
The book is essentially practical in its treatment and it con¬ 
stitutes an accurate record of the researches of its author 
over a period of several years, during which time dozens of 
coils were built and experimented with. 248 pages. Fully 
illustrated. Price, $2.50 


17 


How to Become a Successful Electrician. 

By Frof. T. O’Conor Sloane. An interesting book from 
cover to cover. Telling in simplest language the surest and 
easiest way to become a successful electrician. The studies 
to be followed, methods %f work, field of operation and the 
requirements of the successful electrician are pointed out and 
fully explained. 202 pages. Illustrated. Eighteenth revised 
edition. Cloth. Price, $1.00 

Standard Electrical Dictionary. 

By Prof. T. O’Conor Sloane. Just issued an entirely new 
edition brought up to date and greatly enlarged—as a refer¬ 
ence book this work is beyond comparison as it contains over 
700 pages, nearly 500 illustrations, and definitions of about 
6,000 distinct words, terms and phrases. The definitions are 
terse and concise and includes every term used in electrical 
science. 

In its arrangement and typography the book is very con¬ 
venient. The word or term defined is printed in black faced 
type which readily catches the eye, while the body of the 
page is in smaller but distinct type. The definitions are well 
worded, and so as to be understood by the non-technical 
reader. The general plan is to give an exact, concise defini¬ 
tion, and then amplify and explain in a more popular way. 
Synonyms are also given, and references to other words and 
phrases are made. This work is absolutely indispensable to 
all in any way interested in electrical science, from the 
higher electrical expert to the everyday electrical workman. 
In fact, it should be in the possession of all who desire to keep 
abreast with the progress of this branch of science. Fifteenth 
enlarged edition. Nearly 800 pages. 400 illustrations. 

Price, $5.00 

Storage Batteries Simplified. 

By Victor W. Page. M.S.A.E. This is the most thorough 
and authoritative treatise ever published on this subject. It 
is written in easily understandable, non-technical language so 
that any one may grasp the basic principles of storage bat¬ 
tery action as well as their practical industrial applications. 
All electric and gasoline automobiles use storage batteries. 
Every automobile repairman, dealer or salesman should have 
a good knowledge of maintenance and repair of these im¬ 
portant elements of the motor car mechanism. This book 
not only tells how to charge, care for and rebuild storage 
batteries but also outlines all the industrial uses. Learn 
how they run street cars, locomotives and factory trucks. 
Get an understanding of the important functions they per¬ 
form in submarine boats, isolated lighting plants, railway 
switch and signal systems, marine applications, etc. This 
book tells how they are used in central station standby ser¬ 
vice, for starting automobile motors and in ignition systems. 
Every practical use of the modern storage battery is out¬ 
lined in this treatise. 208 pages, fully illustrated. 

Price, $2.00 

Wiring a House. 

By Herbert Pratt. Shows a house already built; tells just 
how to start about wiring it; where to begin; what wire to 
use; how to run it according to insurance rules; in fact, just 
the information you need. Diiections apply equally to a 
shop. Fourth edition. Price, 35 cents 


18 


Switchboards. 

By William Baxter, Jr. This book appeals to every engi¬ 
neer and electrician who wants to know the practical side 
of things. All sorts and conditions of dynamos, connections 
and circuits are shown by diagram and illustrate just how 
the switchboard should be connected. Includes direct and 
alternating current boards, also those for arc lighting, incan¬ 
descent and power circuits. Special treatment on high voltage 
boards for power transmission. Second edition. 190 pages. 
Illustrated. Price, $2.00 

Telephone Construction, Installation, Wiring, 
Operation and Maintenance. 

By W. H. Radcliffe and H. C. Cushing. This book gives 
the principles of construction and operation of both the 
Bell and Independent instruments; approved methods of 
installing and wiring them; the means of protecting them 
from lightning and abnormal currents; their connection to¬ 
gether for operation as series or bridging stations; and rules 
for their inspection and maintenance. Line wiring and the 
wiring and operation of special telephone systems are also 
treated. 224 pages, 132 illustrations. Second revised edition. 

Price, $1.25 

Wireless Telegraphy and Telephony Simply Ex¬ 
plained. 

By Alfred P. Morgan. This is undoubtedly one of the 
most complete and comprehensive treatises on the subject 
ever published, and a close study of its pages will enable 
one to master all the details of the wireless transmission of 
messages. The author has filled a long-felt want and has 
succeeded in furnishing a lucid, comprehensible explanation 
in simple language of the theory and practise of wireless 
telegraphy and telephony. Third edition. 154 pages, 156 
engravings. Price, $1.25 

Radio Time Signal Receiver. 

By Austin C. Lescarboura. This new book, “A Radio Time 
Signal Receiver,” tells you how to build a simple outfit de¬ 
signed expressly for the beginner. You can build the out¬ 
fits in your own workshop and install them for jewelers 
either on a one-payment or a rental basis. The apparatus 
is of such simple design that it may be made by the average 
amateur mechanic possessing a few ordinary tools. 42 pages. 
Paper. Price, 25 cents 

The Wireless Operators’ Pocketbook of Informa¬ 
tion and Diagrams. 

By Leon W. Bishop. This book begins with a description 
of receiving and transmitting instruments and their use, car¬ 
rying this along to complete sets, with instructions for oper¬ 
ating a station according to the government regulations. The 
problems encountered by radio men, both beginners and ad¬ 
vanced experimenters, have been concentrated into this poc¬ 
ket size book. There is no space wasted, on theories and ob¬ 
solete apparatus. Complete information is given for building 
200-meter transmitters, audions, amplifiers, vacuum tube un¬ 
damped wave telephone and telegraph sets, with notes on 
general radio problems. Over 150 illustrations and hook-ups. 
200 pages. Cloth bound. Fully illustrated. Price $1.50 

19 


FUEL 


Combustion of Coal and the Prevention of Smoke, 

By Wm. M. Barr. This book has been prepared with special 
reference to the generation of heat by the combustion of 
the common fuels found in the United States, and deals 
particularly with the conditions necessary to the economic 
and smokeless combustion of bituminous coals in stationary 
and locomotive steam boilers. The presentation of this 
important subject is systematic and progressive. The arrange* 
ment of the book is in a series of practical questions, to 
which are appended accurate answers, which describe in 
language, free from technicalities, the several proc sses in¬ 
volved in the furnace combustion of American fuels; it 
clearly states the essential requisites for perfect combustion, 
and points out the best methods for furnace construction for 
obtaining the greatest quantity of heat from any given quality 
of coal. Nearly 350 pages, fully illustrated. Fifth edition. 

Price, $1.25 

Smoke Prevention and Fuel Economy. 

By Booth and Kershaw. As the title indicates, this book 
of 197 pages and 75 illustrations deals with the problem of 
complete combustion, which it treats from the chemical and 
mechanical standpoints^ besides pointing out the economical 
and humanitarian aspects of the question. Price, $3.0<h 

GAS ENGINES AND GAS 


Gas, Gasoline and Oil Engines. 

By Gardner D. Hiscox. Revised by Victor W. Pag£. Just 
issued new, revised and enlarged edition. Every user of u 
gas engine needs this book. Simple, instructive and right 
up-to-date. The only complete work on the subject. Tells all 
about internal combustion engineering, treating exhaustively 
on the design, construction and practical application of all 
forms of gas, gasoline, kerosene and crude petroleum-oil 
engines. Describes minutely all auxiliary systems, such as 
lubrication, carburetion and ignition. Considers the theory 
and management of all forms of explosive motors for sta¬ 
tionary and marine work, automobiles, aeroplanes and motor¬ 
cycles. Includes also Producer Gas and Its Production. 
Invaluable instructions for all students, gas-engine owners, 
gas-engineers, patent experts, designers, mechanics, drafts¬ 
men and all having tq, do with the modern power. Illustrated 
by over 400 engravings, many specially made from engineer¬ 
ing drawings, all in correct proportion. Nearly 700 octavo 
pages and 500 engravings. Price, net, $3.00 

Gasoline Engines: Their Operation, Use and Care. 

By A. Hyatt Verrill. A comprehensive, simple and prac¬ 
tical work, treating of gasoline engines for stationary, marine 
or vehicle use;, their construction, design, management, care, 
operation, repair, installation and troubles. A complete glos¬ 
sary of technical terms and an alphabetically arranged table 
of troubles and symptoms form a most valuable and unique 
feature of the book. 5 l A x 7y 2 . Cloth. 275 pages, 152 illus¬ 
trations. Price, $2.00 


20 






Gas Engine Construction. 

Or How to Build a Half-Horse-power Gas Engine. By 
Parsell and Weed. A practical treatise describing the theory 
and principles of the action of gas engines of various types, 
and the design and construction of a half-horse-power gas 
engine, with illustrations of the work in actual progress, 
together with dimensioned working drawings giving clearly 
the sizes of the various details. 300 pages. Third edition. 
Cloth. Price, $3.00 


Chemistry of Gas Manufacture. 

By H. M. Royles. This book covers points likely to arise in 
the ordinary course of the duties of the engineer or manager 
of a gas works not large enough to necessitate the employment 
of a separate chemical staff. It treats of the testing of the 
raw materials employed in the manufacture of illuminating 
coal gas and of the gas produced. The preparation of 
standard solutions is given as well as the chemical and physi¬ 
cal examination of gas coal. 5l4x8J4. Cloth. 328 paces, 
82 illustrations, 1 colored plate. Price, $3.00 

Modern Gas Engines and Producer Gas Plants. 

By R. E. Matitot, M.E. A practical treatise of 320 pages, 
fully illustrated by 175 detailed illustrations, setting .forth 
the principles of gas engines and producer design, the selec¬ 
tion and installation of an engine, conditions of perfect 
operation, producer-gas engines and their possibilities, the 
care of gas engines and producer-gas plants, with a chapter 
on volatile hydrocarbon and oil engines. This book has been 
endorsed by Dugal Clerk as a most useful work for all inter¬ 
ested in gas engine installation and producer gas. $3.00 

The Gasoline Engine on the Farm: Its Operation, 
Repair and Uses. 

By Xeno W. Putnam. A useful and practical treatise on 
the modern gasoline and kerosene engine, its construction, 
management, repair and the many uses to which it can be 
applied in present-day farm life. It considers all the various 
household, shop and field uses of this up-to-date motor and 
includes chapters on engine installation, power transmission 
and the best arrangement of the power plant in reference 
to the work. 5 % x 7j4. Cloth. 527 pages, 179 illustra¬ 
tions. Price, $2.30 

How to Run and Install Two- and Four-Cycle 
Marine, Gasoline Engines. 

By C. Von Culin. New revised and enlarged edition just 
issued. The object of this little book is to furnish a pocket 
instructor for the beginner, the busy man who uses an engine 
for pleasure or profit, but who does not have the time or 
inclination for a technical book, but simply to thoroughly 
understand how to. properly operate, install and care for his 
own engine. The index refers to each trouble, remedy and 
subject alphabetically. Being a quick reference to find the 
cause, remedy and prevention for troubles, and to become 
an expert with his own engine. Pocket size. Paper binding. 

Price, 25 cent# 


21 


Iviudern Gas Tractor, Its Construction, Utility, 
Operation and Repair. 

By Victor W. Page. Treats exhaustively on the design and 
construction of farm tractors and tractor power-plants, and 
gives complete instructions on their care, operation and re¬ 
pair. All types and sizes of gasoline, kerosene and oil 
tractory are described, and every phase of traction engineer¬ 
ing practice fully covered. Invaluable to all desiring re¬ 
liable information on gas motor propelled traction engines 
and their use. Second edition revised by much additional 
matter. 5^4 x 7j4. Cloth, 504 pages, 228 illustrations, 3 
folding plates. Price, $2.50 

GEARING AND CAMS 


Bevel Gear Tables. 

By D. Ag. Engstrom. No one who has to do with bevel 
gears in any way should be without this book. The designer 
and draftsman will find it a great convenience, while to 
the machinist who turns up the blanks or cuts the teeth it 
is invaluable, as all needed dimensions are given and no 
fancy figuring need be done. Third edition. Cloth. $1.25 
• 

Change Gear Devices. 

Oscar E. Perrigo. A book for every designer, draftsman 
and mechanic who is interested in feed changes for any kind 
of machines. This shows what has been done and how. 
Gives plans, patents and all information that you need. Saves 
hunting through patent records and reinventing old ideas. 
A standard work of reference. Third edition. $1.25 

Drafting of Cams. 

By Louis Rouillion. The laying out of cams is a serious 
problem unless you know how to go at it right. This puts 
you on the right road for practically any kind of cam you 
are likely to run up against. Third edition. 35 cents 

HYDRAULICS 


Hydraulic Engineering. 

By Gardner D. Hiscox. A treatise on the properties, power, 
and resources of water for all purposes. Including the meas¬ 
urements of streams; the flow of water in pipes or conduits; 
the horse-power of falling water; turbine and impact water¬ 
wheels; wave-motors, centrifugal, reciprocating and air-lift 
pumps. With 300 figures and diagrams and 36 practical 
tables. 320 pages. Price, $4.50 

ICE AND REFRIGERATION 


Pocketbook of Refrigeration and Ice Making. 

By A. J. Wallis-Taylor. This is one of the latest and 
most comprehensive reference books published on the subject 
of refrigeration and cold storage. It explains the properties 


22 












and refrigerating effect of the different fluids in use, the 
management of refrigerating machinery and the contsruction 
and insulation of cold rooms with their required pipe surface 
for different degrees of cold; freezing mixtures and non- 
freezing brines, temperatures of cold rooms for all kinds of 
provisions, cold storage charges for all classes of goods, ice 
making and storage of ice, data and memoranda for constant 
reference by refrigerating engineers, with nearly one hundred 
tables containing valuable references to every fact and con¬ 
dition required in the installment and operation of a refriger¬ 
ating plant. New edition just published. Price, $2.00 


INVENTIONS—PATENTS 


Inventor’s Manual, How to Make a Patent Pay. 

This is a book designed as a guide to inventors in perfecting 
their inventions, taking out their patents, and disposing of 
them. It is not in any sense a Patent Solicitor’s circular nor 
a Patent Broker’s advertisement. No advertisements of any 
description appear in the work. It is a book containing a 
quarter of a century’s experience of a successful inventor, 
together with notes based upon the experience of many other 
inventors. Revised and enlarged second edition. Nearly 150 
pages. Illustrated. Price $1.25 

KNOTS 


Knots, Splices and Rope Work. 

By A. Hyatt Verrill. This is a practical book giving com¬ 
plete and simple directions for making all the most useful and 
ornamental knots in common use, with chapters on Splicing, 
Pointing, Seizing, Serving, etc. This book is fully illustrated 
with 154 original engravings, which show how each knot, 
tie or splice is formed, and its appearance when finished. 
The book will be found of the greatest value to campers, 
yachtsmen, travelers or Boy Scouts, in fact, to anyone having 
occasion to use or handle rope or knots for any purpose. 
The book is thoroughly reliable and practical, and is not 
only a guide but a teacher. It is the standard work on the 
subject. Second edition revised. 128 pages, 154_ original 
engravings. Price, $1.00 

LATHE WORK 


Complete Practical Machinist. 

By Joshua Rose. The new, twentieth revised and enlarged 
edition is now ready. This is one of the best-known books 
on machine-shop work, and written for the practical work¬ 
man in the language of the workshop. It gives full, practi¬ 
cal intsructions on the use of all kinds of metal-working tools, 
both hand and machine, and tells how the work should be 
properly done. It covers lathe work, vise work, drills and 
drilling, taps and dies, hardening and tempering, the making 
and use of tools, tool grinding, marking out work, machine 
tools, etc. No machinist’s library is complete without this 
volume. 547 pages, 432 illustrations. Price $3.00 

23 







The Lathe—its Design, Construction and Opera 
^tion, With Practical Examples of Lathe Work, 

By Oscar E. Perrigo. A new revised edition, and the only 
complete American work on the subject, written by a man 
who knows not only how work ought to be done, but who 
also knows how to do it, and how to convey this knowledge 
to others. It is strictly up-to-date in its descriptions and 
illustrations. Lathe history and the relations of the lathe 
to manufacturing are given; also a description of the various 
devices for feeds and thread cutting mechanisms from early 
efforts in this direction to the present time. Lathe design is 
thoroughly discussed, including back gearing, driving cones, 
thread-cutting gears, and all the essential element of the 
modern lathe. The classification of lathes is taken up, giving 
the essential differences of the several types of lathes includ¬ 
ing, as is usually understood, engine lathes, bench lathes, 
speed lathes, forge lathes, gap lathes, pulley lathes, forming 
lathes, multiple-spindle lathes, rapid-reduction lathes, precision 
lathes, turret lathes, special lathes, electrically-driven lathes, 
etc. In addition to the complete exposition _ on construction 
and design, much practical matter on lathe installation, care 
and operation has been incorporated in the enlarged new edi¬ 
tion. All kinds of lathe attachments for drilling, milling, 
etc., are described and complete instructions are given to 
enable the novice machinist to grasp the art of lathe oper¬ 
ation as well as the principles involved in design. A number 
of difficult machining operations are described at length and 
illustrated. The new edition has nearly 500 pages and 350 
illustrations. Price, $3.00 

Turning and Boring Tapers. 

By Fred H. Colvin. There are two ways to turn tapers; 
the right way and one other. This treatise has to do with 
the right way; it tells you how to start the work properly, 
how to set the lathe, what tools to use and how to use them, 
and forty and one other little things that you should follow. 
Fourth edition. Price, 35 cents 


LIQUID AIR 


Liquid Air and the Liquefaction of Gases. 

By T. O’Conor Sloane. The third revised edition of this 
book has just been issued. Much new material is added 
to it; and the all important uses of liquid air and gas pro¬ 
cesses in modern industry, in the production especially of 
nitrogen compounds, are described. The book gives the his¬ 
tory of the theory, discovery, and manufacture of Liquid 
Air, and contains an illustrated description of all the ex¬ 
periments that have excited the wonder of audiences all over 
the country. It shows how liquid air, like water, is car¬ 
ried hundreds of miles and is handled in open buckets. It 
tells what may be expected from it in the near future. A 
book that renders simple one of the most perplexng chemical 
problems of the century. Startling developments illustrated 
by actual experiments. It is not only a work of scientific 
interest and authority, but is intended for the general read¬ 
er, being written in a popular style—easily understood by 
everyone. 400 pages fully illustrated. Price, $3.00 


24 



LOCOMOTIVE ENGINEERING 


Air-Brake Catechism. 

By Robert II. Blackall. This book is a standard text book. 
It is the only practical and complete work published. Treats 
on the equipment manufactured by the Westinghouse Air 
Brake Company, including the E-T Locomotive Brake Equip¬ 
ment, the Iv (Quick-Service) Triple Valve for freight ser¬ 
vice; the L High Speed Triple Valve; the P-C Passenger 
Brake Equipment, and the Cross Compound Pump. The 
operation of all parts of the apparatus is explained in detail 
and a practical way of locating their peculiarities and rem¬ 
edying their defects is given. Endorsed and used oy air¬ 
brake instructors and examiners on nearly every railroad 
in the United States. Twenty-sixth edition. 411 pages, fully 
illustrated with folding! plates and diagrams, New edition. 

Price, $2.50 


Application of Highly Superheated Steam to 
Locomotives. 

By Robert Garbe. A practical book which cannot be recom¬ 
mended too highly to those motive-power men who are 
anxious to maintain the highest efficiency in their locomo¬ 
tives. Contains special chapters on Generation of Highly 
Superheated Steam; Superheated Steam and the Two-Cylinder 
Simple Engine; Compounding and Superheating; Designs of 
Locomotive Superheaters; Constructive Details of Locomo¬ 
tives Using Highly Superheated Steam. Experimental and 
Working Results. Illustrated with folding plates and tables. 
Cloth. Price, $3.00 

Combustion of Coal and the Prevention of Smoke. 

By Wm M. Barr. To be a success a fireman must be “Light 
on Coai.” He must keep his fire in good condition, and 
prevent, as far as possible, the smoke nuisance. To do this, 
he should know how coal burns, how smoke is formed and 
the proper burning of fuel to obtain the best results. He 
can learn this, and more too, from Barr’s “Combustion . of 
Coal” 'It is an absolute authority on all questions relating 
to the firing of a locomotive. Fifth edition. Nearly 350 
pages, fully illustrated. Price, $1.25 


Diary of a Round-House Foreman. 

Bv T S C Reilly. This is the greatest book of railroad experi¬ 
ences ever published. Containing a fund of information and 
suggestions along the line of handling men, organizing, etc.^, 
that one cannot afford to miss. 176 pages. Price, $1.2o 


Link Motions, Valves and Valve Setting. 

Bv Fred II. Colvin, Associate Editor of “American Machin- 
is?” A handv book that clears up the mysteries of valve 
setting Shows the different valve gears in use, how they 
work and why. Piston and slide valves of different types 
are illustrated and explained. A book that every railroad 
man in the motive-power department ought to. have. Fill y 
illustrated. New revised and enlarged edlt.on^ust 


25 






Traiii Rule Examinations Made Easy. 

By G. E. Collingwood. This is the only practical work on 
train rules in print. Every detail is covered, and puzzling 
points are explained in simple, comprehensive language, mak¬ 
ing it a practical treatise for the train dispatcher, engine- 
man, trainman and ail others who have to do with the move¬ 
ments of trains. Contains complete and reliable information 
of the Standard Code of Train Rides for single track. Shows 
signals in colors, as used on the different roads.. Explains 
fully the practical application of train orders, giving a clear 
and definite understanding of all orders which may be used. 
Second edition revised. 256 pages. Fully illustrated with 
train signals in colors. . Price, $1.50 

Locomotive Boiler Construction. 

By Frank A. Kleinhans. The only book showing how loco¬ 
motive boilers are built in modern shops. Shows all types of 
boilers used; gives details of construction; practical facts, 
such as life of riveting punches and dies, work done per 
day, allowance for bending and flanging sheets and other 
data that means dollars to any railroad man. Second edition. 
451 pages, 334 illustrations. Six folding plates. Cloth. 

Price, $3.50 

Locomotive Breakdowns and Their Remedies. 

By Geo. L. Fowler. Revised by Wm. W. Wood, Air-Brake 
Instructor. Pocket edition. It is out of the question to try 
and tell you about every subject that is covered in this 
pocket edition of Locomotive Breakdowns. Just imagine 
all the common troubles that an engineer may expect to 
happen some time, and then add all of the unexpected ones, 
troubles that could occur, but that you had never thought 
about, and you will find that they are all treated with the 
very best methods of repair. Walschaert Locomotive Valve 
Gear Troubles, Electric Headlight Troubles, as well as Ques¬ 
tions and Answers on the Air Brake, are all included. Eighth 
edition. 294 pages. Fully illustrated. Price, $1.25 

Locomotive Catechism. 

By Robert Grimshavv. Twenty-eighth revised and enlarged 
edition. This may well be called an encyclopedia of the 
locomotive. Contains over 4,000 examination questions with 
their answers, including among them those asked at the first, 
second and third year’s examinations. 825 pages, 437 illus¬ 
trations and 3 folding plates. Price, $2.50 

Westinghouse E. T. Air-Brake Instruction Pocket- 
book Catechism. 

By Wm. W. Wood, Air-Brake Instructor. A prajtical work 
containing examination questions and answers on the E. T. 
Equipment. Covering what the E. T. Brake is. How it 
should be operated. What to do when defective. Not a 
question can be asked of the engineman up for promotion 
on either the No. 5 or the No. 6 E. T. equipment that is not 
asked and answered in the book. If you want to thoroughly 
understand the E. T. equipment get a copy of this book. It 
covers every detail. . Makes air-brake troubles and examina¬ 
tions easy. Fully illustrated with colored plates, showing 
various pressures. Cloth. Price, $2.00 


26 


Practical Instructor and Reference Book for 
Locomotive Firemen and Engineers. 

Hy Chas F. Lockhart. An entirely new book on the loco¬ 
motive. It appeals to every railroad man, as it tells him how 
things are done and the right way to do them. Written by 
a man who has had years of practical experience in locomotive 
shops and on the road firing and running. The information 
given in this book cannot be found in any other similar 
treatise. Eight hundred and fifty-one questions with their 
answers are included, which will prove specially helpful to 
those preparing for examination. 368 pages, 88 illustrations, 
doth. Price, $2.00 

Prevention of Railroad Accidents, or Safety in 
Railroading. 

By Georce Bradshaw. This book is a heart-to-heart talk 
with railroad employees, dealing with facts, not theories, and 
showing the men in the ranks, from every-day experience, 
how accidents occur and how they may be avoided. Tne 
book is illustrated with seventy original photographs and 
drawings showing the safe and unsafe methods of work. No 
visionary schemes, no ideal pictures. Just plain facts and 
practical suggestions are given. Every railroad employee 
who reads the book is a better and safer man to have in 
railroad service. It gives just the information which will be 
the means of preventing many injuries and deaths. All 
railroad employees should procure a copy; read it, and do 
their part in preventing accidents. 169 pages. Pocket size. 
Fully illustrated. Price, 50 cent* 

Walschaert Locomotive Valve Gear. 

By Wm. W. Wood. If you would thoroughly understand 
the Walschaert Valve Gear, you should possess a copy of 
this book. The author divides the subject into four divisions, 
as follows: I. Analysis of the gear. II. Designing and 
erection of the gear. III. Advantages of the gear. IV. Ques¬ 
tions and answers relating to the Walschaert Valve Gear. 
This book is specially valuable to those preparing for pro¬ 
motion. Third edition. 245 pages. Fully illustrated. Cloth. 

Price, $2.00 


MACHINE SHOP PRACTICE 


Modern Machine Shop Construction, Equipment 
and Management. 

By Oscar E. Perrigo. The only work published that describes 
the Modern Machine Shop or Manufacturing Plant from the 
time the grass is growing on the site intended for it until the 
finished product is shipped. Just the book needed by those 
contemplating the erection of modern shop buildings, the 
rebuilding and reorganization of old ones or the introduction 
of Modern Shop Methods, Time and Cost Systems. It is a 
book written and illustrated by a practical shop man for 
practical shop men who are too busy to read theories and 
want facts. It is the most complete all-around book of. its 
kind ever published. Second edition. 384 pages, 219 original 
and specially-made illustrations. Price, $5.00 


27 




EVERY PRACTICAL MAN NEEDS 

A MAGAZINE WHICH WILL TELL HIM 
HOW TO MAKE AND DO THINGS 


HAVE US ENTER YOUR SUBSCRIPTION 

to the best mechanical magazine on the market. 
Only One Dollar and Fifty Cents a year for 
twelve numbers. Subscribe to-day to 

EVERYDAY ENGINEERING 


A monthly magazine devoted to practical mechanics for 
everyday men. Its aim is to popularize engineering as a 
science, teaching the elements of applied mechanics and 
electricity in a straightforward and understandable manner. 
The magazine maintains its own experimental laboratory, 
where the devices described in articles submitted to the 
Editor are first tried out and tested before they are pub¬ 
lished. This important innovation places the standard of 
the published material very high, and it insures accuracy 
and dependability._ 

The magazine is the only one in this country that spe¬ 
cializes in practical model building. Articles in past issues 
have given comprehensive designs for many model boats, 
including submarines and chasers, model steam and gasoline 
engines, electric motors and generators, etc., etc. This 
feature is a permanent one in the magazine. 

Another popular department is that devoted to automobiles 
and airplanes. Care, maintenance, and operation receive 
full and authoritative treatment. Every article is written 
from the practical, everyday man rtandpoint, rather than 
from that of the professional. 

The magazine entertains while it instructs. It is a journal 
of practical, dependable information, given in a style that 
it may be readily assimilated and applied by the man with 
little or no technical training. The aim is to place before 
the man who leans toward practical mechanics a series of 
concise, crisp, readable talks on what is going on and how 
it is done. These articles are profusely illustrated with 
clear, snappy photographs, specially posed to illustrate the 
subject in the magazine’s own studio by its own staff of 
technically-trained illustrators and editors. 

Tlie subscription price of the magazine is one dollar 
and fifty cents per year of twelve numbers. Sample 
copy sent on receipt of fifteen cents. 

Enter your subscription to this practical magazine with your 
bookseller. 


28 







Machine Shop Arithmetic. 

By Colvin-Cheney. Most popular book for shop men. 
shows how all shop problems are worked out and “why ” 
Includes change gears for cutting any threads; drills, taps, 
fu ln j an t torec fits; metric system of measurements and 
threads. Used by all classes of mechanics and for instruction 
m Y. SNl. C. A. and other schools. Seventh edition. 131 
pages. Price, 60 cents 

Abrasives and Abrasive Wheels. 

By Fred B. Jacobs. A new book for everyone interested in 
abrasives or grinding. A careful reading of the book will 
not only make mechanics better able to use abrasives intel¬ 
ligently, but it will also tell the shop superintendent of 
many short cuts and efficiency-increasing kinks. The econ¬ 
omic advantage in using large grinding wheels are fully 
explained, together with many other things that will tend to 
give the superintendent or workman a keen insight into 
abrasive engineering. 340 pages, 200 illustrations. This if 
an indispensable book for every machinist. Price, $3.00 

American Tool Making and Interchangeable 
Manufacturing. 

By J. V. Woodworth. In its 500-odd pages the one subject 
only, Tool Making, and whatever relates thereto, is dealt with. 
The work stands without a rival. It is a complete practical 
treatise on the art of American Tool Making and system of 
interchangeable manufacturing as carried on to-day in the 
United States. In it are described and illustrated all of the 
different types and classes of small tools, fixtures, devices 
and special appliances which are in general use in all ma¬ 
chine-manufacturing and metal-working establishments where 
economy, capacity and interchangeability in the production 
of machined metal parts are imperative. The science of jig 
making is exhaustively discussed, and particular attention 
is paid to drill jigs, boring, profiling and milling fixtures 
and other devices in which the parts to be machined are 
located and fastened within the contrivances. All of the 
tools, fixtures and devices illustrated and described have 
been or are used for the actual production of work, such 
as parts of drill presses, lathes, patented machinery, type¬ 
writers, electrical apparatus, mechanical appliances, brass 
goods, composition parts, mould products, sheet metal arti¬ 
cles, drop forgings, jewelry, watches, medals, coins, etc. 
Second edition. 531 pages. Price, $4.50 

Henley’s Encyclopedia of Practical Engineering 
and Allied Trades. 

Edited by Joseph G. Horner, A.M.I.Mech.E. This book 
covers the entire practice of Civil and Mechanical Engineer¬ 
ing. The best known experts in all branches of engineering 
have contributed to these volumes. The Cyclopedia is admir¬ 
ably well adapted to the needs of the beginner and the self- 
taught practical man, as well as the mechanical engineer,, 
designer, draftsman, shop superintendent, foreman and 
machinist. 

It is a modern treatise in five volumes. Handsomely bound 
in half morocco, each volume containing nearly 500 pages, 
with thousands of illustrations, including diagrammatic and 
sectional drawings with full explanatory details. 

Price, $30.00. For the complete set of five volumes. 

29 


THE WHOLE FIELD OF MECHANICAL 
MOVEMENTS COVERED BY MR. 
HISCOX’S TWO BOOKS 


We publish two books by Gardner D. Hiscox that will 
keep you from “inventing” things that have been d^ne be¬ 
fore, and suggest ways of doing things that you have not 
thought of Lelore. Many a man spends time and money, 
pondering over some mechanical problem, only to learn, after 
he has solved the problem, that the same thing has been 
accomplished and put in practice by others long before. Time 
and money spent in an effort to accomplish what has al¬ 
ready been accomplished are time and money lost. The 
whole field of mechanics, every known mechanical movement, 
and practically every device is covered by these two books. 
If the thing you want has been invented, it is illustrated in 
them. If it hasn’t been invented, then you’ll find in them 
the nearest things to what you want, some movement or 
device that will apply in your case, perhans; or which will 
give you a key from which to work. No book or set of 
books ever published is of more real value to the inventor, 
draftsman or practical mechanic than the two volumes de¬ 
scribed below. 

Mechanical Movements, Powers and Devices. 

By Gardner D. Htscox. This is a collection of 1,890 
engravings of different mechanical motions and appliances, 
accompanied by appropriate text, making it a book of great 
value to the inventor, the draftsman, and to all readers- 
with mechanical tastes. The book is divided into eighteen- 
sections or chapters, in which the subject-matter is classified 
under the following heads: Mechanical Powers; Transmis¬ 
sion of Power; Measurement of Power; Steam Power; Air 
Power Appliances; Electric Power and Construction; Navi¬ 
gation and Roads; Gearing; Motion and Devices; Control¬ 
ling Motion; Horological; Mining; Mill and Factory Appli¬ 
ances; Construction and Devices; Drafting Devices; Miscel¬ 
laneous Devices, etc. Fifteenth edition. 400 octavo pages. 

Price, $4.00 

Mechanical Appliances, Mechanical Movements 
and Novelties of Construction. 

By Gardner D. Hiscox. This is a supplementary volume 
to the one upon mechanical movements. Unlike the first 
volume, which is more elementary in character, this volume 
contains illustrations and descriptions of many combina¬ 
tions of motions and of mechanical devices and appliances 
found in different lines of machinery, each device being 
shown by a line drawing with a description showing its 
working parts and the method of operation. From the 
multitude of devices described and illustrated might be men¬ 
tioned, in passing, such items as conveyors and elevators, 
Prony brakes, thermometers, various types of boilers, solar 
engines, oil-fuel burners, condensers, evaporators, Corliss 
and other valve gears, governors, gas engines, water motors 
of various descriptions, air ships, motors and dvnamos, 
automobiles and motor bicvcles, railwav lock signals, car 
couplers, link and gear motions, ball bearings, breech block 
mechanism for heaw guns, and a large accumulation of 
others of equal importance. 1,000 specially made engravings. 
396 octavo pages. Fourth revised edition. Price, $4.00 

30 




“Shop Kinks.” 


By Robert Grimshaw. This shows special methods of doing 
work of various kinds, and releasing cost of production. Has 
hints and kinks from some of the largest shops in this/ 
country and Europe. You are almost sure to find some that 
apply to your work, and in such a way as to save time and 
trouble. 400 pages. Fifth edition. Cloth. Price, $3.00 


Machine Shop Tools and Shop Practice. 

By W. H. Vandervoort. A woik of 555 pages and 673 illus¬ 
trations, describing in every detail the construction, opera¬ 
tion, and manipulation of both hand and machine tools. 
Includes chapters on filing, fitting, and scraping surfaces; 
on drills, reamers, taps, and dies; the lathe and its tools; 
planers, shapers, and their tools; milling machines and cut¬ 
ters; gear cutters and gear cutting; drilling machines and 
drill work; grinding machines and their work; hardening and 
tempering; gearing, belting, and transmission machinery; 
useful data’ and tables. Sixth, edition. Cloth. Price, $4.25 


Model Making. 

By Raymond Francis Yates. A new book for the mechanic 
and model maker. This is the first book of its kind to be 
published in this country and all those interested in model 
engineering should have a copy. The first eight chapters are 
devoted to such subjects as Silver Soldering ? Heat Treatment 
of Steel, Lathe Work, Pattern Making, Grinding, etc. The 
remaining twenty-four chapters describe the construction of 
various models such as rapid fire naval guns, speed boats, 
model steam engines, turbines, etc. 

This book must not be confused with those describing the 
construction of toys now on the market. It is a practical 
treatise on model engineering and construction. 400 pages. 
301 illustrations. Price, $3.00 


The Modern Machinist. 

By John T. Usher. This book might be called a compen¬ 
dium of shop methods, showing a variety of special tools and 
appliances which will give new ideas to many mechanics from 
the superintendent down to the man at the bench. It will 
be found a valuable addition to any machinist’s library, and 
should be consulted whenever a new or difficult job is to 
be done, whether it is boring, milling, turning, or planing, 
as they are all treated in a practical manner. Fifth edition. 
320 pages, 250 illustrations. Cloth. Price, $2.50 


Threads and Thread Cutting. 

By Colvin and Stabel. This clears up many of the mysteries- 
of thread cutting, such as double and triple threads, internal 
threads, catching threads, use of hobs, etc.. Contains a lot 
of useful hints and several tables. Third edition. 35 cents; 

31 


/ 


MARINE ENGINEERING 


The Naval Architect’s and Shipbuilder’s Pocket- 
book 

of Formulae, Rules, and Tables and Marine Engineer’s and 
Surveyor’s Handy Book of Reference. By Clement Mack- 
row and Lloyd Woollard. The eleventh revised and en¬ 
larged edition of this most comprehensive work has just been 
issued. It is absolutely indispensable to all engaged in the 
Shipbuilding Industry, as it condenses into a compact form 
all data and formulae that are ordinarily required. The book 
is completely up to date, including among other subjects a 
section on Aeronautics. 750 pages, limp leather binding. 

Price, $6.00 net 

Marine Engines and Boilers, Their Design and 
Construction. The Standard Book. 

By Dr. G. Bauer, Leslie S. Robertson and S. Bryan Don¬ 
kin. In the words of Dr. Bauer, the present work owes its 
origin to an oft felt want of a condensed treatise embodying 
the theoretical and practical rules used in designing marine 
engines and boilers. The need of such a work has been 
felt by most engineers engaged in the construction and work¬ 
ing of marine engines, not only by the younger men, but also 
by those of greater experience. The fact that the original 
German work was written by the chief engineer of the 
famous Vulcan Works, Stettin, is in itself a guarantee that 
this book is in all respects thoroughly up-to-date, and that 
it embodies all the information which is necessary for the 
design and construction of the highest types of marine en¬ 
gines and boilers. It may be said that the motive power 
which Dr. Bauer has placed in the fast German liners that 
have been turned out of late years from the Stettin Works 
represent the very best practice in marine engineering of 
the present day. The work is clearly written, thoroughly 
systematic, theoretically sound; while the character of the 
plans, drawings, tables, and statistics is without reproach. 
The illustrations are careful reproductions from actual work¬ 
ing drawings, with some well-executed photographic views of 
completed engines and boilers. 744 pages, 550 illustrations, 
and numerous tables. Cloth. Price, $10.00 net 


MANUAL TRAINING 


Economics of Manual Training. 

By Louis Rouillion. The only book that gives just the in¬ 
formation needed by all interested in manual training, re¬ 
garding buildings, equipment and supplies. Shows exactly 
what is needed for all grades of the work from the Kinder¬ 
garten to the High and Normal School. Gives itemized lists 
of everything needed and tells just what it ought to cost. 
Also shows where to buy supplies. Illustrated. Second 
edition. Cloth. Price, $2.00 


32 






MINING 


Ore Deposits, With a Chapter on Hints to Pros¬ 
pectors. 

By J. P. Johnson. This book gives a condensed account of 
the ore deposits at present known in South Africa. It is 
also intended as a guide to the prospector. Only an ele¬ 
mentary knowledge of geology and some mining experience 
are necessary in order to understand this work. With these 
qualifications, it will materially assist one in his search for 
metalliferous mineral occurrences and, so far as simple ores 
are concerned, should enable one to form some idea of the 
possibilities of any they may find. Illustrated. Cloth. $2.00 

Practical Coal Mining. 

By T H. Cockin. An important work, containing 428 pages 
and 213 illustrations, complete with practical details, which 
will intuitively impart to the reader not only a general 
knowledge, of the principles of coal mining, but also con¬ 
siderable insight into allied subjects. The treatise is posi¬ 
tively up-to-date in every instance, and should be in the 
hands, of every colliery engineer, geologist, mine operator, 
superintendent, foreman, and all others who are interested 
in or connected with the industry. Third edition. $2.50 

Physics and Chemistry of Mining. 

By T. H. Byrom. A practical work for the use of all pre¬ 
paring for examinations in mining or qualifying for colliery 
managers’ certificates. The aim of the author in this excel¬ 
lent book is to place clearly before the reader useful and 
authoritative data which will render him valuable assistance 
in his studies. -The only work of its kind published. The 
information incorporated in it will prove of the greatest 
practical utility to students, mining engineers, colliery man¬ 
agers, and all others who are specially interested in the 
present-day treatment of mining problems. Second edition, 
revised. 188 pages, illustrated. Price, $2.00 

PATTERN MAKING 


Practical Pattern Making. 

By F. W. Barrows. This book, now in its second edition, 
is a comprehensive and entirely practical treatise on the 
subject of pattern making, illustrating pattern work in both 
wood and metal, and with definite instructions on the use 
of plaster of paris in the trade. It gives specific and detailed 
descriptions of the materials used by pattern makers and 
describes the tools; both those for the bench and the more 
interesting machine tools; having complete chapters on the 
lathe, the circular saw and the band saw. It gives many 
examples of pattern work, each one fully illustrated and 
explained with much detail. These examples, in their great 
variety, offer much that will be found of interest to all 
pattern makers, and especially to the younger ones, who are 
seeking information on the more advanced branches of their 
trade. Containing nearly 350 pages and 170 illustrations. 
Second edition, revised and enlarged. Price, $2.50 

33 






PERFUMERY 


Henley’s Twentieth Century Book of Receipts, 
Formulas and Processes. 

Edited by G. D. IIiscox. The most valuable techno-chemical 
receipt book published. Contains over 10,000 practical re¬ 
ceipts, many of which will prove of special value to the 
.perfumer. Price, $4.00 

Perfumes and Cosmetics, Their Preparation and 
Manufacture. 

By G. VV. Askinson, Perfumer. A comprehensive treatise, 
in which there has been nothing omitted that could be of 
value to the perfumer or manufacturer of toilet preparations. 
Complete directions for making handkerchief perfumes, 
smelling-salts, sachets, fumigating pastiles; preparations, for 
the care of the skin, the mouth, the hair, cosmetics, hair 
dyes and other toilet articles are given, also a detailed 
description of aromatic substances; their nature, tests of 
purity, and wholesale manufacture, including a chapter on 
synthetic products, with formulas for their use. A book of 
general, as well as professional interest, meeting the wants 
not only of the druggist and perfume manufacturer, but also 
of the general public. Fourth edition much enlarged and 
brought up-to-date. Nearly 400 pages, illustrated. $5.00 


PLUMBING 


Standard Practical Plumbing. 

By R. M. Starbuck. This is a complete treatise and covers 
the subject of modern plumbing in all its branches. It 
treats exhaustively on the skilled work of the plumber and 
the theory underlying plumbing devices and operations, and 
commends itself at once to anyone working in any branch 
•of the plumbing trade. A large amount of space is devoted 
to a very complete and practical treatment of the subjects of 
hot water supply, circulation and range boiler work. Another 
valuable feature is the special chapter on drawing for 
plumbers. The illustrations, of which there are three hun¬ 
dred and forty-seven, one hundred being full-page plates, 
were drawn expressly for this book and show the most 
modern and best American practice in plumbing construction. 

Cloth, 406 pages, 347 illustrations. Price, $3.50 

Mechanical Drawing for Plumbers. 

By R. M. Starbuck. A concise, comprehensive and practical 
treatise on the subject of mechanical drawing in its various 
modern applications to the work of all who are in any way 
connected with the plumbing trade. Nothing will so help 
the plumber in estimating and in explaining work to cus¬ 
tomers and workmen as a knowledge of drawing, and to the 
workman it is of inestimable value if he is to rise above his 
position to positions of greater responsibility. 150 illus¬ 
trations. Price, $2.00 


34 







Modern Plumbing Illustrated. 

By R. M. Starbuck. The author of this book, Mr. R. M. 
Starbuck, is one of the leading authorities on plumbing in 
the United States. The book represents the highest standard 
of plumbing work. A very comprehensive work, illustrating 
and describing the drainage and ventilation of dwellings, 
apartments and public buildings. The very latest and most 
approved methods in all branches of sanitary installation are 
given. The standard book for master plumbers, architects, 
builders, plumbing inspectors, boards of health, boards of 
plumbing examiners and for the property owner, as well 
as the workman and apprentice. It contains fifty-seven en¬ 
tirely new and large full pages of illustrations with descrip¬ 
tive text, all of which have been made specially for this 
work. These plates show all kinds of modern plumbing work. 
Each plate is accompanied by several pages of text, giving 
notes and practical suggestions, sizes of pipe, proper measure¬ 
ments for setting up work, etc. Suggestions on estimating 
plumbing construction are also included. 407 octavo pages, 
fully illustrated by 57 full-page engravings. Price, ij>5.00 


RECIPE BOOK 

=—■ ■■ ■ : * 


Henley’s Twentieth Century Book of Recipes, 
Formulas and Processes. 

Edited by Gardner D. Hiscox. The most valuable techno¬ 
chemical formulae book published, including over 10,000 se¬ 
lected scientific, chemical, technological and practical recipes 
and processes. This book of 800 pages is the most complete 
book of recipes ever published, giving thousands of recipes 
for the manufacture of valuable articles for everyday use. 
Hints, helps, practical ideas and secret processes are revealed 
•within its pages. It covers every branch of the useful arts 
and tells thousands of ways of making money and is just the 
bock everyone should have at his command. The pages are 
filled wfih matters of intense interest and immeasurable prac¬ 
tical value to the photographer, the perfumer, the painter, 
the manufacturer of glues, pastes, cements and mucilages, 
the physician, the druggist, the electrician, the brewer, the 
engineer, the foundryman, the machinist, the potter, the 
tanner, the confectioner, the chiropodist, the manufacturer 
Of chemical novelties and toilet preparations, the dyer, the 
electroplater, the enameler, the engraver, the provisioned the 
glass worker, the goldbeater, the watchmaker and jeweler, 
the ink manufacturer, the optician, the farmer, the daityman, 
the paper maker, the metal worker, the soap maker, the 
veterinary surgeon, and the technologist in general. A book 
to which you may turn with confidence that you will find 
what you are looking for. A mine of information up-to-date 
in every resoect. Contains an immense number of formulas 
that every one ought to have that are not found in any other 
work. New edition. Cloth binding. p r i ce . $4.00 


35 




RUBBER 


Henley’s Twentieth Century Book of Receipts, 
Formulas and Processes. 

Edited by Gardner D. Hiscox. Contains upward of 10,000 
practical receipts, including among them formulas on arti¬ 
ficial rubber. Price, $4.00 

Rubber Hand Stamps and the Manipulation of 
India Rubber. 

Bv T. O’Conor Sloane. This book gives full details of all 
points, treating in a concise and simple manner the elements 
of nearly everything it is necessary to understand for a 
commencement in any branch of the India rubber manu¬ 
facture. The making of all kinds of rubber hand stamps, 
small articles of India rubber, U. S. Government composi¬ 
tion, dating hand stamps, the manipulation of sheet rubber, 
tov balloons, India rubber solutions, cements, blackings, 
renovating varnish, and treatment for India rubber shoes, 
etc.; the hektograph stamp inks, and miscellaneous notes, 
with a short account of the discovery, collection and manu¬ 
facture of India rubber are set forth in a manner designed 
to be readily understood, the explanation being plain and 
simple. Third edition. 175 pages, illustrated. Price, $1.25 

SAWS 


Saw Filing and Management of Saws. 

By Robert Grimshaw. A practical hand book on filing, 
gumming, swaging, hammering and the brazing of band saws, 
the speed, work, and power to run circular saws, etc. A 
handy book for those who have charge of saws, or for those 
mechanics who do their own filing, as it deals with the proper 
shape and pitches of saw teeth of all kinds and gives many 
useful hints and rules for gumming, setting, and filing, and is 
a practical aid to those who use saws for any purpose. Third 
edition, revised and enlarged. Illustrated. Price, $1.25 

SCREW CUTTING 


Threads and Thread Cutting. 

By Colvin and Stable. This clears up many of the mysteries 
of thread cutting, such as double and triple threads, internal 
threads, catching threads, use of hobs, etc. Contains a lot of 
useful hints and several tables. Third edition. 35 cents 

STEAM ENGINEERING 


Horse-pcwer Chart. 

Shows the horse-power of any stationary engine without 
calculation. No matter what the cylinder diameter or stroke; 
the steam pressure or cut-off; the revolutions, or whether 
condensing or non-condensing, it’s all there. Easy to use, 
accurate, and saves time and calculations. Especially useful 
to engineers and designers. Price, 50 cent*. 


36 










Steam Engine Troubles. 

hil H * , It: ? s safe to ' sa y tha t no book has ever 

hi e ® n PV bllshed wh 1C h gives th& practical engineer such valul 

and trnnK Pre TV, nS1Ve inf ° rmat ?°". on stelm engine design 
and troubles. There are descriptions of cylinders, valves 

pistons, frames, pillow blocks and other bearings, connect¬ 
ing rods, wristplates, dashpots, reachrods, valve gears, vov- 
throttle and emergency valves, safety stops, 

nfrT? tl ’ k 01 r S ’- etC> If , there is any trouble with these 
parts, the book gives you the reasons and tells how to remedy 
them. 350 pages, 276 illustrations. Price, $2.50 


American Stationary Engineering. 

By W. E. Crane. A t new book by a well-known author, 
begins at the boiler room and takes in the whole power plant. 
Contains the result of years of practical experience in ali 
sorts of engine rooms and gives exact information that cannot 
be found elsewhere. It’s plain enough for practical men and 
yet of value to those high in the profession. Has a complete 
examination for a license. Third edition revised and en¬ 
larged. 345 pages. 131 illustrations. Cloth. Price, $2.50 


Steam Engine Catechism. 

By Robert Grimshaw. This volume of 413 pages is not 
only a catechism on the question and answer principle, but 
it contains formulas and worked-out answers for all the steam 
problems that appertain to the ooeration and management of 
the steam engine. Sixteenth edition. Price, $2.00 


Boiler Room Chart. 

By Geo. L. Fowler. A chart—size 14 x 28 inches—showing 
in isometric perspective the mechanism belonging in a modern 
boiler room. The various parts are shown broken or re¬ 
moved, so that the internal construction is fully illustrated. 
Each part is given a reference number, and these, with the 
corresponding name, are given in a glossary printed at the 
sides. Price, 25 cents 


Engine Runner’s Catechism. 

By Robert Grimshaw. Tells how to erect, adjust and run 
the principal steam engines in use in the United States. The 
work is of a handy size for the pocket. To yc ung engineers 
this catechism will be of great value, especially to those who 
may be preparing to go forward to be examined for certifi¬ 
cates of competency; and to engineers. generally it will be 
of no little, service, as they will find in this volume more 
really practical and useful information than is to be found 
anvwhere else within a like compass. 387 pages. Seventh 
edition. Price, $2.00 


Modern Steam Engineering in Theory and Prac¬ 
tice. 

By Gardner D. Hiscox. This is a complete and practical 
work issued for stationary engineers and firemen dealing 
with the care and management of boilers, engines, pumps, 
superheated, steam, refrigerating machinery, dynamos, motors, 
elevators, air compressors, and all. other branches with which 
the modern engineer must be familiar. . Nearly 200 questions 
with their answers on steam.and electrical engineering, likely 
to be asked by the examining board, are included. Third 
mdition. 487 pages, 405 engravings. Cloth! Price, $8.50 


Steam Engineer’s Arithmetic. 

By Colvin-Cheney. A practical pocket book for the steam 
engineer. Shows how to work the problems of the engine 
room and shows “why.” Tells how to figure horse-power 
of engines and boilers; area of boilers; has tables of areas and 
circumferences; steam tables; has a dictionary of engineering 
terms. Puts you onto all of the little kinks in figuring what¬ 
ever there is to figure around a power plant. Tells you about 
the heat unit; absolute zero; adiabatic expansion; duty of 
engines; factor of safety; and 1,001 other things; and every¬ 
thing is plain and simple—not the hardest way to figure, 
but the easiest. Second edition. Price, 60 cents 


STEAM HEATING and 'VENTILATING 


Practical Steam, Hot-Water Heating and Ven¬ 
tilation. 

By A. G. King.. This book has been prepared for the use 
of all engaged in the) business of steam, hot-water heating 
and ventilation. Tells how to get heating contracts, how to 
install heating and ventilating apparatus, the best business 
methods to be used, with “Tricks of the Trade” for shop 
use. Rules and data for estimating radiation and cost and 
such tables and information . as make it an indispensable 
work for everyone interested in steam, hot-water heating and 
ventilation. It describes all the principal systems of steam, 
hot-water, vacuum, vapor and vacuum-vapor heating, together 
with the new accelerated systems of hot-water circulation, 
including chapters on up-to-date methods of ventilation and 
the fan or blower system of heating and ventilation. Second 
edition. 367 pages, 300 detailed engravings. Cloth. $3.50 

500 Plain Answers to Direct Questions on Steam, 
Hot-Water, Vapor and Vacuum Heating Prac¬ 
tice. 

By Alfred G. King. This work, just off the press, is ar¬ 
ranged in question and answer form; it is intended as a 
guide and text-book for the younger inexperienced fitter 
and as a reference book for all fitters. All long and tedious 
discussions and descriptions formerly considered so important 
have been eliminated, and the theory and laws of heat and 
the various old and. modern methods and appliances used 
for heating and ventilating are treated in a concise manner. 
This is the standard Question and Answer examination book 
on Steam and Hot Water Heating, etc. 200 pages, 127 illus¬ 
trations. Octavo. Cloth. Price, $2.00 


STEEL 


Hardening, Tempering, Annealing and Forging 
of Steel. 

By J. V. Woodworth. A book containing special directions 
for the successful hardening and tempering of all steel tools. 
Milling cutters, taps, thread dies, ^earners, both solid and 
shell, hollow mills, punches and die*-. ^nd all kinds of sheet- 


33 






metal working tools shear blades, saws, fine cutlery and 
metal-cutting tools of all descriptions, as well as for all 
implements of steel, both large and small, the simplest, and 
most satisfactory hardening and tempering processes are 
presented. 320 pages, 250 illustrations. Fourth edition! 
Cl0th - Price, $3.00 

Steel: Its Selection, Annealing, Hardening and 
Tempering. 

Markham. This work was formerly known as 
he American Steel Worker, but on the publication of the 
new, revised edition, the publishers deemed it advisable to 
change its title to a more suitable one. This is the standard 
work on hardening, tempering, and annealing steel of all 
kinds. this book tells how to select, and how to work, 
temper, harden, and anneal steel for everything on earth. 
It is the standard book on selecting, hardening, and tem¬ 
pering all grades of steel. 400 pages. Very fully illustrated. 
Fourth edition. Price, $3.00 


TRACTORS 


The Modern Gas Tractor. 

By Victor W. Pag£:. A complete treatise describing all 
types and sizes of gasoline, kerosene, and oil tractors. Con¬ 
siders design and construction exhaustively, gives complete 
instruction for care, operation ard repair, outlines all prac¬ 
tical applications on the road and in the field. The best 
and latest work on farm tractors and tractor power plants. 
A work needed by farmers, students, blacksmiths, mechanics, 
salesmen, implement dealers, designers, and engineers. Second 
edition revised and much enlarged. 504 pages. Nearly 300 
illustrations and folding plates. • Price, $2.50 

TURBINES 

= ■ - = 

Marine Steam Turbines. 

By Dr. G. Bauer and O. Lasche. Assisted by E. Ludwig 
and H. Vogel. Translated from the German and edited 
by M. G. S. Swallow. The book is essentially practical and 
discusses turbines in which the full expansion of steam 
passes through a number of separate turbines arranged for 
driving two or more shafts, as in the Parsons system, and 
turbines in which the complete expansion of steam from inlet 
to exhaust pressure occurs in a turbine on one shaft, as in 
the case of the Curtis machines. It will enable a designer 
to carry out all the ordinary calculation necessary for the 
construction of steam turbines, hence it fills a want which 
is hardly met by larger and more theoretical works. Numer¬ 
ous tables, curves and diagrams will be found, which explain 
with remarkable lucidity the reason why turbine blades are 
designed as they are, the course which steam takes through 
turbines of various types, the thermodynamics of steam tur¬ 
bine calculation, the influence of vacuum on steam consump¬ 
tion of steam turbines, etc. In a word, the very information 
which a designer and builder of steam turbines most requires. 
Large octavo, 214 pages. Fully illustrated and containing 
18 tables, including an entropy chart. Price, $4.00 net 

« 


39 






The Most Valuable Techno-Chemical Recipe 
Book Ever Offered to the Public! 


Henley’s Twentieth Century Book 


RECIPES, FORMULAS 
AND PROCESSES 



Price $4.00 



This book of 800 pages is the most complete Book of Recipes 
ever published, giving thousands of recipes for the manu¬ 
facture of valuable articles for every-day use. Hints, Helps, 

Practical Ideas and S e c r e t 
Processes are revealed within 
its pages. It covers every 
branch of the useful arts and 
tells thousands of ways of mak¬ 
ing money and is just the book 
everyone should have at his 
command. 

The pages are filled with 
matters of intense interest and 
immeasurable practical value to 
the Photographer, the Perfumer, 
the Painter, the Manufacturer 
of Glues, Pastes, Cements and 
Mucilages, the Physician, the 
Druggist, the Electrician, the 
Brewer, the Engineer, the 
Foundryman, the Machinist, the 
Potter, the Tanner, the Con¬ 
fectioner, the Chiropodist, the 
Manufacturer of Chemical Nov¬ 
elties and Toilet Preparations, 
the Dyer, the Electroplater, the 
Enameler, the Engraver, the Provisioner, the Glass Worker, 
the Goldbeater, the Watchmaker and Jeweler, the Ink Manu¬ 
facturer, the Optician, the Farmer, the Dairyman, the Paper 
Maker, the Metal Worker, the Soap Maker, the Veterinary 
Surgeon and the Technologist in general. 

A book to which you may turn with confidence that you 
will find what you are looking for. A mine of information, 
up-to-date in every respect. Contains an immense number 
of formulas that every one ought to have that are not found 
in any other work. 


10,000 


Practical Formulas and Processes 
The Best Way to Make Everything 


ONE USEFUL RECIPE WILL BE WORTH MORE 
THAN TEN TIMES THE PRICE OF THE BOOK 
























